Games | Dr Eric Silverman

Apr 13 2020

Games, Shogi

Dai Shogi, Part I: How to Play

Following on from my previous two posts about Chu Shogi (Part I, Part II), I plan to provide a full annotated Chu Shogi game for you. This is still in the works, but Chu Shogi games are long, so that post will take quite a while to prepare.

In the meantime, I’m going to work in parallel on material for other historical Shogi variants. Today I’m going to introduce you to Dai Shogi, Chu Shogi’s big brother and one of the earliest forms of the game. Dai Shogi is often given short shrift by the Shogi variant community, who largely dismiss it as a slower, more boring version of Chu Shogi; hopefully by the end of this post I can convince you that this isn’t a completely fair characterisation.

One of the advantages of learning Dai Shogi is that if you know Chu Shogi, you can learn the basics of Dai Shogi in no time at all. That means this post will be a bit more concise than the last two. However — excuse me while I put this in bold type on a separate line for emphasis —

You must know how to play Chu Shogi in order to make sense of this post!

Now that’s out of the way, let’s get started!

The Origins of Dai Shogi

As mentioned in the first Chu Shogi article, we are aware of a large version of Shogi dating all the way back to the mid-12th century. In the latter part of the 12th century the Nichureki was published, and this document describes an early form of Dai Shogi now generally referred to as Heian Dai Shogi.

Heian Dai Shogi was played on a 13×13 board with 34 pieces per player, with 13 types of pieces available. Much of the board was therefore empty, and the pieces moved slowly for the most part, so most attempts at reconstructing this game find it to be rather glacially paced.

However, clearly the Shogi playing community of the time realised this fairly early on, and various diary references to Dai Shogi in the 14th century suggest it was a well-regarded game, so we suspect that the game evolved into its more robust 15×15 form by that time. Dai Shogi is presented in detail alongside Chu Shogi in the Shōgi Rokushu no Zushiki (象棋六種之図式), originally published in 1443, which you can see below:

During the 15th century Dai Shogi was considered the most distinguished form of the game, as described by George Hodges:

“Large Shogi eventually became popular enough to be referred to simply as ‘Shogi’…. Similar references abound throughout the 15th century, and indeed many imply that Little Shogi was generally regarded as merely a boys’ game.”
–George Hodges, Shogi Magazine

Dai Shogi eventually lost popularity to Chu Shogi, which offered a lot of the same ingredients in a tighter package. Chu Shogi was then the dominant form of Shogi until the late 16th century, when the introduction of the drop rule in Sho Shogi (small Shogi) turned the Shogi world on its head. From that point onward, Dai Shogi largely vanished from the Shogi world, although we know it was still being played into the 19th century as it appears in a few famous woodcuts around that time.

Dai Shogi today has experienced somewhat of a revival, though much less so than Chu Shogi or Tenjiku Shogi. Dai Shogi can be purchased and played relatively easily today largely thanks to the efforts of George Hodges, who disseminated information on Shogi variants around the Western world in the 1970s and 80s. While in today’s fast-paced world a full game of Dai Shogi can be tough to organise, thanks to the efforts of dedicated Shogi fans worldwide there are still ways to get a game going via the internet or in real life.

The Rules

As you might expect from a game I keep calling ‘Chu Shogi’s big brother’, Dai Shogi is played on a bigger board: 15 x 15, with 225 squares, substantially larger than Chu Shogi’s 12 x 12 board with 144 squares. Of course the starting armies are larger too; each player begins with 65 pieces of 29 different types, which is again a significant increase from Chu Shogi’s 46 pieces per player of 21 different types. Including promotions Dai Shogi requires you to remember 36 different moves, a decent step up from 28 in Chu Shogi.

The starting position of a Dai Shogi game looks like this:

Diagram 1: Dai Shogi board with 2-kanji pieces.

There’s clear similarities here to the Chu Shogi setup: two Go-Betweens at the front, then a complete row of pawns, then a massive army lurking behind with the King at the very back. However, because Dai Shogi has an odd number of files, the King can sit directly in the centre on the back rank.

Here is the initial position with all pieces flipped over to show their promoted sides:

Diagram 2: Dai Shogi board with pieces flipped to show their promoted sides (2-kanji pieces).

Just like in Chu Shogi, only the Lion, Free King and King don’t promote. If you look closely you may notice a bunch of pieces promoting to Gold General — more on that later.

Now let’s zoom in and look at one player’s starting setup in detail, this time with 1-kanji pieces for better readability:

: Diagram 3: Dai Shogi initial position for one player (1-kanji pieces).

: Diagram 4: Dai Shogi initial position for one player, with pieces flipped to show their promoted sides (1-kanji pieces).

If you look more closely at Diagram 3, you will notice that the pieces are shuffled around somewhat compared to Chu Shogi. The central position of the King is a bit more convenient, particularly given that the King starts already ensconced in a Basic Castle (two Blind Tigers and a Drunk Elephant in front, and flanked by two Gold Generals). The Free King and Lion are now in two different rows, and to either side of them are several new pieces. More new pieces are sitting close to the left and right edges of the board on the first and fourth ranks. When we look down at Diagram 4, we can see that all of these new pieces promote to Gold General. Along with these eight new piece types, Dai Shogi contains every piece type that is in Chu Shogi, and they have identical promotions in Dai as well.

The Basics

Rather than go through all the basic rules in full, which are nearly identical to Chu Shogi, I will just mention the key points:

Objective: The goal of the game is to capture all of the opponent’s royal pieces — their King or Crown Prince (if applicable). If a player has both a King and Crown Prince on the board, both must be captured for the other player to win. A player may also win by eliminating every non-royal piece from their opponent’s army (the Bare King Rule).
Making Moves: Black (at the bottom of the board in our diagrams) always moves first. Players take it in turns to move one piece in their army in accordance with its movement abilities. Pieces may not move into or through squares occupied by friendly pieces. If that player’s piece moves into the same square as an opposing piece, that opposing piece is captured and removed from the game. As in Chu Shogi, there are no drops in Dai Shogi; captured pieces are removed from the board and play no further part in the game afterward.
Promotion: If a player moves a piece in their promotion zone — which in Dai Shogi consists of the five furthest ranks from that player’s starting position — they may choose to promote that piece by flipping it over. That piece now becomes a different piece, as indicated by the characters on the promoted side. Once a piece is promoted it may not un-promote. If a player chooses not to promote a piece on its initial move into the promotion zone, the piece may promote on a subsequent move if it A) moves out of the zone, then back in, or B) captures an enemy piece within the zone.
If a player chooses not to promote a piece and that piece reaches a point where it can no longer move, then that piece simply becomes a ‘dead piece’ and sits in place for the rest of the game, or until it is captured. This applies to pieces that cannot move backwards, like the Stone General, Knight, Lance, and Pawn.
Repetition: Repeating a board position with the same player to move is forbidden. This is more strict than the official rules for Chu Shogi, which allow four repetitions. Wikipedia claims that this rule does not apply when a player is in check. A player may pass their turn using the Lion’s abilities, but two passes in a row are not possible in Dai Shogi, since that would create the same position with the same player to move.
Lion-Trading Rules: There are no Lion-trading rules in Dai Shogi! The larger board means the Lion doesn’t dominate quite so much as in Chu, although the Lion is still very dangerous in endgame situations.

The New Pieces

To learn Dai Shogi, we also need to learn the moves and promotions of the eight new pieces. These new pieces are quite easy to remember:

: Diagram 5: The eight new pieces of Dai Shogi (2-kanji pieces)

: Diagram 6: The eight new pieces of Dai Shogi (1-kanji pieces)

There’s a few key points to note with these new pieces:

The Knight is back — Players of standard Shogi may have noticed there were no Knights in Chu Shogi, but the Knight has returned in Dai Shogi. The Dai Shogi Knight moves like a Chess Knight, but only forward.
Longer-range weak pieces — Two of the new pieces, the Violent Ox and the Flying Dragon, are unique in that they are the only short-ranged pieces that can move 1 or 2 spaces in certain directions. This can be helpful when facing off against an opposing group of weak pieces, as they exert a slightly larger influence across the board.
Simple promotions — All eight pieces promote to Gold General. This means promotion is a little less exciting than with some other short-range pieces, but nonetheless a Gold General is a useful defensive piece due to its good coverage of adjacent squares, and a powerful checkmating threat when near the enemy King.

All of these pieces promote to Gold General, but not all of them have strictly upward-compatible moves; in other words, some pieces’ unpromoted moves are not a subset of the Gold General’s moves, meaning that you may not want to promote them in certain circumstances.

Upward-compatible pieces: Stone General, Iron General, Evil Wolf, Angry Boar
Non-upward-compatible pieces: Knight, Cat Sword, Violent Ox, Flying Dragon

The upward-compatible pieces, however, should always be promoted. Becoming a Gold General substantially increases their movement powers, so there’s no reason to leave them unpromoted.

If you know Chu Shogi, then getting to grips with these pieces should be very easy for you. They all have simple moves and the same promotion. To make things even easier for you, I’ve created reference sheets for all the Dai Shogi pieces in two versions: dai-shogi-reference (1-kanji) and dai-shogi-reference (2-kanji). Click the links to download PDF versions, or click the thumbnails below for very high-resolution PNG images.

: Dai Shogi reference sheet (1-kanji pieces)

: Dai Shogi reference sheet (2-kanji pieces)

Why play Dai Shogi?

Amongst the admittedly small Shogi variant player community, Dai Shogi has a reputation for being just a slower and/or more boring form of Chu Shogi. When looking for information on the game, one will frequently stumble on comments like this one, taken from the ChessVariants.com page for Dai Shogi:

“The extra pieces are rather weak, and promote to the also weak Gold General. As a result of this, and due to the longer time it takes the many steppers to cross the larger board, Dai Shogi is a much slower game than Chu. It is thus not surprising the latter quickly surpassed Dai Shogi in popularity.”

Or this comment buried within the Chu Shogi page on Wikipedia:

“As stated earlier, this game is based on dai shogi and all of the pieces of this game can be found in dai shogi. The eight types of pieces that were removed were all rather weak and all promoted to gold generals. Furthermore, the larger board of dai shogi makes the slow-moving step movers even slower. All of this made for comparatively dull gameplay.”

I cannot stress enough that I strongly disagree with this assessment. Dai Shogi is definitely a longer game, generally speaking; a typical Chu Shogi game might last 300 moves, whereas a Dai Shogi game can reach 400-500 moves, or sometimes substantially longer. Here is the final position of a game I played online that I won after 568 moves:

dai-shogi-aftermath-568moves copy

When you see a number as large as that, you may be turned off. But that final position shows how violently thrilling a good Dai Shogi game can be. My 65-strong starting army was whittled down to only 16 pieces, and this was due to some extravagant piece sacrifices throughout the game to gain positional advantage and a series of bloody exchanges. During the game my Lion captured about a dozen opposing pieces before finally being dispatched. If you look at my castle at the bottom of the board, you can see the final desperate lunge of my opponent’s last-minute attack before I finally clinched the victory. So yes, the game was long, but it was a nail-biter throughout. After that game I could never call Dai Shogi ‘boring’ or ‘slow’.

I should be clear that I would still generally recommend Chu Shogi over Dai Shogi — Chu is tighter, shorter, and just a devastatingly good game. But compared to Chu Shogi, Dai Shogi offers a new experience — more intricate and strategic, while losing none of the tactical complexity of Chu. In fact, I propose there are some significant advantages to Dai Shogi for the aspiring Shogi fanatic:

Bigger board, bigger armies: Yes, having a larger board does lengthen the game, and there are more pieces to remember. But the larger board also opens up more strategic flexibility. Openings are less sharp than in Chu, and you have more time to build up an attacking force and prepare your defences. The larger army also makes the game a bit more forgiving — early mistakes can be mitigated more easily, as individual pieces are less impactful on such a large board.
Convenient starting array — Dai Shogi has an odd number of rows and columns on the board, unlike Chu, so the starting position is more symmetrical. The King begins in the dead centre on the back rank, and he starts the game already in the Basic Castle formation we know and love from Chu. That means it is viable to simply leave the King where he is and focus your opening on developing your attacking pieces, rather than spending moves on collecting your defensive pieces together. The new short-range pieces also start the game closer to the front lines, so gathering your forces to the front is not too onerous. In general the starting formation feels very carefully and cleverly designed, and it enables opening play to maintain a good pace, without much need for back-rank defensive reshuffles.
No Lion-trading rules — The ChessVariants.com page on Dai Shogi appears to cite this as a negative, bizarrely. The Lion-trading rules in Chu Shogi, while they serve a very important purpose and definitely benefit the game, are also difficult to learn, filled with weird exceptions, and at times counter-intuitive. Dai Shogi can dispense with them entirely, since the Lion is still powerful here but not totally dominant, and that means we get to enjoy its powers without worrying about any rules-lawyering being needed in unusual board situations.
A nice stepping-stone to larger games: Dai Shogi is far from the biggest form of Shogi. I will cover these in later articles, but you can see a bit of information on the larger Shogi games in my introduction to Shogi. Most of these larger beasts are very significant leaps in complexity from Chu Shogi; Dai Dai Shogi, for example, has 64 types of pieces in the starting position, compared to 21 in Chu Shogi. Dai Shogi brings some of the benefits of these larger games — greater strategic scope, more expansive opening strategies — but can be easily learned in an afternoon if one already knows Chu Shogi. This makes Dai Shogi an ideal introduction to the large Shogi games, which beyond simply being immense, are actually well-designed and fascinating games to play.

So, taking all those points into account, I do believe Dai Shogi offers something of its own character. Dai may not have the extravagant piece variety of Dai Dai Shogi, or the all-powerful Emperor of Maka Dai Dai Shogi, but it does offer a compelling, strategic gameplay experience without much more mental overhead than Chu Shogi. Dai Shogi is by any measure an extremely large member of the Chess family, yet it manages to be so without becoming unmanageable. I’d even say that in some ways it may be more forgiving for beginners than Chu Shogi, given that mistakes hurt a bit less here and opening play is more freeform, and not needing to learn the Lion-trading rules is a nice bonus.

R. Wayne Schmittberger, perhaps one of the most experienced large Shogi players in recent history, does prefer Chu Shogi but offers this endorsement of Dai Shogi’s attractions:

“The extra space between the starting forces and the greater number of pieces permit greater flexibility in playing the opening than in Chu, and hence greater scope for creativity.”

Ultimately, it’s technically true that Dai Shogi is basically ‘Chu Shogi, only bigger’, but I would emphasise that the game offers greater scope for strategic intrigue and complexity — and yet still remains comprehensible. In that respect I think it has a character all its own, and is well worth taking the time to explore.

Basic tips for beginners

To be perfectly honest, there’s not a whole lot of information out there about how to play Dai Shogi at a high level. However, the game’s similarity to Chu Shogi at least offers a strong starting point. What I will do here is highlight some key points of Chu strategy, and describe how to adapt them to Dai Shogi; I will also talk a bit about how to utilise the new pieces.

The Opening

As mentioned above, the opening in Dai Shogi is a bit more freeform than in Chu Shogi, thanks to the larger board area. However, the same opening principles used in Chu Shogi can be usefully applied here:

Don’t neglect your short-range pieces: In Dai Shogi you have a wider Pawn line, so be sure to bring forward some of your new short-range pieces to fortify your Pawns. As in Chu Shogi, any weak points in your front line will be vigorously attacked by the opposing Lion, so try not to allow any obvious weaknesses to develop. Out of the eight new pieces, the stronger ones — the Flying Dragon, Violent Ox, Evil Wolf, and Iron General — can be used as active attackers as you steadily advance your Pawn line. The weaker ones — the Stone General, Angry Boar, Cat Sword and Knight — are still valuable up front, but more for force of numbers than as the vanguard. Knights in particular are easy to lose by mistake, as they jump forward relatively quickly but in a very limited way; advance the Knights carefully, and avoid jumping them into positions that reduce their already limited mobility.
Keep your King safe: The King starts in a Basic Castle from move one, so rather than shuffling around your pieces to form a castle you can instead focus on fortifying this pre-existing structure. As in Chu, bolstering that formation with your Silvers, or even with your Dragon Kings or Dragon Horses can be useful.
Place your Lion high and central: Despite the somewhat weaker influence of the Lion in Dai, and its greater susceptibility to capture due to the lack of anti-trading rules, the Lion is still well-placed at the front of the action. Use your Lion to stake a claim to the centre and exert its influence as strongly as you can. The Lion can easily exploit weaknesses in the enemy front line to claim some quick material gains, and its presence can force the enemy to channel their forces away from the centre, allowing you to fortify your defences on the appropriate side of the board. Just be aware of the threat of a Lion trade if your opponent gets fed up; sometimes you may want to jump the Lion behind the Pawns to fortify your front line whilst staying out of trading range.

The old Lucky Dog Games site on Dai Shogi has some sample openings, which I’ve diagrammed below for your convenience:

Diagram 7: Position after 1.P-9j P-7f 2.P-7j P-9f 3.DH-12n DH-9g 4.EW-10l Ln-9e 5.P-10j Ln-8g 6.P-6j P-4f 7.Ph-9k P-3f 8.Ph-10k EW-6d 9.EW-9k EW-7e 10.Ln-6k P12f

In this position we see a fairly solid early opening from both sides, with several central Pawn advances backed up by the Lion. Both players have brought their Evil Wolves forward as well to reinforce the advanced Pawns. The centre looks set to be a stage for some Lion manoeuvring; the later stages of the opening may see the players developing an attacking posture on one side of the board, leaving the Lions and Wolves to battle over the centre.

Diagram 8: Position after 1.P-9j P-7f 2.DH-7i P-9f 3.EW-10l Ln-9e 4.EW-9k Ln-8g 5.EW-8j Ln-10i
6.Ln-9k Lnx11j-12i 7.N-13m P-8f 8.P-6j Ky-7e 9.P-4j P-6f 10.P-3j Ph-8c

Here White has jumped the Lion directly into the action, capturing a Go-Between on the left side in the process. Black has chosen to lock down the centre instead, with a well-placed Lion and an Evil Wolf and Dragon Horse advanced as well. The advanced Pawns on the right suggest Black may be planning to develop an attack along this flank.

Granted this is very early in a Dai Shogi opening — an opening in this game can easily last 100 moves or more — but at this stage I feel Black is more solid. White’s Lion has made a small material gain but is unprotected and could be harassed, allowing a further gain of tempo for Black. Black meanwhile has an early hold on the centre and has moved various pieces rather than jumping the Lion all over the place, giving them better piece development overall.

Diagram 9: 1.P-13j P-7f 2.FD-12j Ln-7e 3.P-10j Ln-8g 4.Ln-10k Ln-6i5.P-14j P-9f 6.VO-14k Lnx5j-4i 7.N-3m DH-7g 8.Ln-8i P-10f9.B-9j FD-12b 10.R-14l P-12f

In this position White has again spent several tempi unleashing the Lion, this time grabbing a Go-Between on the right side. Black is clearly developing an attack along the left side, having advanced a Violent Ox backed up by a Rook. Black again holds the centre, this time with a Lion protected by a Bishop. The Lion’s influence also helps restrict White’s Dragon Horse.

Again I’d suggest Black has made better use of their early turns here. White’s Lion does restrict Black’s development along the right side, but Black has already made gains of space on the left and can freely develop their attack over there. Black’s Lion is dominant in the centre, and they are strong on the 14th file as well.

Diagram 10: Position after 1.P-9j P-7f 2.P-8j P-9f 3.P-6j Ln-9e 4.Ln-8k DK7d-8c 5.P-3j EW-7d
6.DH-4n P-8f 7.EW-6l EW-8e 8.B-7j N-3c 9.GB-5i P-4f 10.EW-6k P-8g

Finally, in this last example both players have advanced in a more cautious way. Both Lions are centrally placed and protecting the Pawn line. Both have brought their Evil Wolves forward to support Pawn advances. Neither player has obvious weaknesses; Black appears to be preparing an advance on the right side, whereas White is advancing in the centre, perhaps to prepare a higher Lion placement.

These opening positions are instructive examples of the extremely varied play that is possible in the Dai Shogi opening. Despite the larger board, players can exert pressure quite early in the game, forcing the opponent to commit their attacking forces to one side or another. Piece placement can vary enormously depending on players’ particular style, so maintaining flexibility is important. As in Chu, advancing the weaker pieces is critical to developing a strong attacking posture, and those pieces should serve to reinforce your Pawn line. As we can see in these examples, the Evil Wolf is a useful piece to develop in the early going, and is conveniently placed to support early Pawn advances.

The Middlegame

The middlegame of Dai Shogi is a spectacularly complicated affair, so it’s difficult to offer much more than very basic concepts here. In general, we will apply the principles we learned in Chu Shogi, while bearing in the mind the consequences of the larger board:

Advance methodically: Perhaps even more true in Dai than in Chu. Your army has a larger and more varied array of short-range pieces, including two that have a two-square movement range (the Flying Dragon and the Violent Ox), so be sure to advance these on the front where you are developing your attack. On such a large board it’s hard to resist the temptation to advance your Pawns quickly to get things going, but try not to fall victim to that impulse. A solid Pawn line supported by your stronger short-range pieces — Evil Wolves, Violent Oxen, Flying Dragons, Iron Generals, Copper Generals — will gain you space much more effectively than a hurried Pawn push with little support. The Lion is slower in this game but still has an insatiable appetite for Pawns and Go-Betweens!
Avoid pointless material losses: This is another general Chu Shogi principle that works well in Dai. Patience is a virtue here, and even though the larger armies make individual material losses less impactful, at some stage you will need to exert force on some part of the board to gain space and cramp your opponent’s defences; doing so is much harder if you lack the numbers. If you do end up down in material, avoid major exchanges of pieces; instead, try to gain enough space to promote some pieces, which can make up for the lost material value. Conversely, if you hold a material advantage, try to force an exchange; this will open up lines of attack, but your material edge will ensure you are better able to exploit this new space than your opponent.
Don’t rush toward promotion: The bigger board of Dai means that gaining space all the way to the promotion zone will take more time and effort. In general, the larger board means long-range pieces have even more power than in Chu, so advancing pieces with a long-range promotion will be very helpful in the later stages of your attack. For this reason you want to ensure that your pieces with strong promotions can promote safely, so take the time to secure space at the edge of the promotion zone before dashing forward to upgrade your forces. As in Chu, some pieces with strong promotions should be held back until the endgame starts — namely the Gold General, Phoenix, Kirin and Drunk Elephant. The Golds and the Drunk Elephant are very useful defensive pieces, so don’t promote them unless they have a clear path toward the promotion zone and your King is otherwise secured. The Phoenix and Kirin promote to the strongest pieces in the game, so keep them back behind your front line until the board opens up; even then, keep them protected as much as possible as they head for promotion, as their movements are rather slow and awkward. As in Chu, a promoted Vertical Mover is a powerful addition to your attack.
Keep your Lion centralised and patrolling: This general principle from Chu is still fairly useful here, but as you can see from the sample openings above, the larger board area does permit some different Lion adventures at times. The challenge with the Lion in Dai is to maximise its impact in the opening, where it is safer from long-range attack due to the interposing pawns on both sides, and in the endgame, where a Lion assault on the King is often decisive. In the heat of the late middlegame, where pieces are dropping like flies and numerous lines of attack are opening up, make sure to keep your Lion safe from sniping attacks from long-range pieces. Do not be afraid to drop the Lion back to safety temporarily; better to keep the Lion alive deep into the endgame than to valiantly sacrifice it for early material gains. You will be glad you protected your Lion as you enter the endgame, particularly if a spicy mutual-checkmating-attack situation develops.
Don’t forget about defence! A useful principle to keep in mind in Dai as well as Chu — or in fact in any Chess-type game, where defence is less glamorous than attack and is all too easily neglected. As in Chu, your Rooks and Side-Movers are extremely useful for defence; R. Wayne Schittberger recommends dropping your Rooks back to the third rank to patrol in front of the King’s castle. Side-Movers can be placed on the fourth and fifth ranks to mount a solid defence against the enemy Lion. Keeping short-range pieces in defence of your edge pieces — the Lance and Reverse Chariot — can be useful too, in order to prevent an exchange along the edge opening a pathway to promotion for your opponent.

The Endgame

The basic principles of the endgame in Dai are very similar to Chu: advance your Golds and Drunk Elephant when it is safe to do so; advance your Lion toward the enemy King; and promote your forces when possible to make your attacking army more dangerous. The major addition in Dai are the new short-range pieces, in particular those with unusual moves that may not benefit from a promotion.

The puzzles below illustrate the powers of these new pieces in a checkmating attack. The Violent Oxen and Flying Dragons can be useful here, in that their slightly longer range can help restrict the movement of the enemy King. These puzzles are the only Dai-Shogi-specific tsumeshogi I’ve managed to find to date, and they didn’t come with solutions; I’ve dug these out of my archives and diagrammed the solutions so you can check your answers. I’ll present the four puzzles below, and solutions will come after my concluding section:

: Puzzle 1. Hint: remember the promotion rules.

: Puzzle 2. Hint: the Knight leaps into action.

: Puzzle 3. Hint: the Stone General is the foundation of your attack.

: Puzzle 4. Hint: the Violent Ox lives up to its name.

Final thoughts

Dai Shogi occupies a somewhat unfortunate position in the Shogi variant world; Dai has a little brother that’s extremely highly regarded, and larger siblings with very unique pieces and patterns of play. That leaves Dai somewhat at sea, being a larger version of Chu but without the craziness of other large variants like Tenjiku Shogi or Dai Dai Shogi.

However, I hope this article conveys the attractions that Dai Shogi can offer, and shows that it’s more than just Chu’s bigger, slower predecessor. Dai is a highly strategic game with a dynamic opening phase, and while the new pieces are of the weaker variety, they do have some unique characteristics that can come into play. Dai Shogi is also a great stepping-stone toward the aforementioned larger, crazier variants, given that it shares their size and strategic richness but is much easier to learn.

If you want to play Dai Shogi online, your options are unfortunately rather limited — you can play via PBEM on Richard’s PBEM Server (Dai Shogi is a sub-option of Chu Shogi). You can also play via this Japanese site, although you’ll need to have Flash enabled (my 568-move game above was played there).

For real-life play, your best option is to purchase physical sets with plastic pieces and sturdy vinyl boards from Angela Hodges. Real wooden Dai Shogi boards are still available in Japan, although the prices are significant, and wooden pieces are even more expensive; both the pieces and boards tend to be rare, so if you’re keen then I suggest buying them as soon as you see them in stock. The Go and Shogi store I linked there is very accustomed to international orders, and the proprietor speaks English well, so I can easily recommend them if you fancy a traditional wooden set.

Now that we’ve covered essentially all the basics of Dai Shogi in this post, my next Dai Shogi post will be an annotated game. The game in question is, unsurprisingly, very long, so this post will take some time to prepare. In the meantime, I will focus on presenting an annotated Chu Shogi game and will start my introduction to Tenjiku Shogi.

Tsumeshogi Solutions

Puzzle 1 Solution

The first puzzle may take a few tries to get; there are actually quite a few options for the first move, but only the Kirin sacrifice ensures the King cannot escape to the left and delay the mate. Remembering that the Dragon Horse is still able to promote in this position helps to find the pathway to the solution. In the end, the combination of the powerful Horned Falcon and the lowly Stone General is enough to secure the win.

Puzzle 2 Solution

The second puzzle provides a moment for the Knight to shine. Again the promotion rules are paramount here; the Reverse Chariot and Lance are both just outside the zone, so giving double-check with the Knight forces the King into position to be trapped by their promoted forms. The Violent Ox serves to box the King in and protect the Knight from capture.

Puzzle 3 Solution

Puzzle 3 is a bit more of a challenge; there are a number of blind alleys one can wander down before discovering the most forcing line. The solution makes clever use of the Stone Generals to pull the King out of the corner and restrict his escape squares. The final mate is a deadly combination of Dragon King and Stone General.

Puzzle 4 Solution

The final puzzle has a 9-move solution, which seems intimidatingly long, but in actuality the solution is pretty straightforward (both literally and figuratively). The key to this one lies in recognising the Vertical Mover’s dominance of the 2-file; with that file locked down, the Violent Ox can use its 2-square range to simply push the King back until the Side Mover must take the Ox, and then the Bishop’s diagonal is unblocked, allowing the mate.

Tagged Dai Shogi, Games, Shogi, Shogi Variants

Apr 09 2020

2 Comments

Games, Shogi

Chu Shogi, Part II: Attack and Defence

“Despite this complexity, after playing [Chu Shogi] a few times, one begins to feel that each piece has its own personality, and that not one of the pieces could have been left out without harming the character and charm of the game. A game as large as Chu could easily have been dull and ponderous; instead, it is rich in tactics, deep in strategy, and exciting to play.”

–R. Wayne Schmittberger, Shogi Magazine, October 1986

Following on from my previous article on Chu Shogi, this time I’d like to get into a bit more detail about attack and defence strategies. My main vehicle for this will be a discussion of building defensive castles, then attacking and utilising your pieces’ strengths, and finally some instructive checkmate puzzles (tsumeshogi) that demonstrate the powers of the unique Chu Shogi pieces in the endgame.

Before we get started, two quick clarifications:

Notation: in the diagrams below I’ll be using Western-style notation, as described on the Wikipedia page. This system is pretty easy to understand — Chess players please note, however, that a ‘+’ at the end of a move means the piece was promoted, not that it gave check. Also I’m used to Japanese notation, so I may not get it right all the time — if I make any mistakes, please shout and I’ll fix them.
Move numbering: Most Western sources use Chess-style move counting, where each numbered ‘move’ is actually a move pair, one from Black and one from White. I find this confusing when dealing with tsumeshogi puzzles, so I’m sticking with Shogi/Go-style move counting, where a move is simply a move from one player.

Building Castles in Chu Shogi

For us Chess players, building defensive structures for the King is made substantially easier by the presence of the castling move, which enables us to tuck the King safely behind one of the Rooks in a single stroke. For Shogi players, castling is not a move, but a process; players spend quite a few moves re-arranging their pieces to build fortresses around their King. Often these castles require substantial material investment and cover quite a bit of board space; Shogi castles need to be solid, given that the ability to drop captured pieces anywhere means that deadly attacks can occur very suddenly.

Chu Shogi of course is closer to the latter than the former — there is no specific castling move, and instead players must construct castles themselves. In Chu Shogi there are no drops, but the Lion Power pieces do present significant dangers; they can deliver mate even when pieces block their direct path to the King!

Below are some example castle formations that you may encounter in a Chu Shogi game:

Diagram 1: Chu Shogi castle formations

The Basic Castle is very commonly seen in Chu Shogi games, and is easily built: simply bring the Drunk Elephant in front of the King, flank it with your Blind Tigers, and keep your Gold Generals on either side of the King. The Golds are somewhat better placed one square out from the King, as in the centre of the top row in Diagram 1. The Basic Castle may be basic, but when combined with Side-Movers parked on the 3rd and 4th ranks and some patrolling Rooks as well, this formation can provide a decent amount of safety.

However, this castle has some weak points that become apparent if an attacking Lion breaks through and has the support of a long-range piece. The long-range piece pins the Drunk Elephant to the King, preventing it from capturing the attacking Lion (since that would expose the King to immediate capture):

chu-shogi-enhanced-castle-explanation-01

Diagram 2: weak points in the Basic Castle.

The immobile Drunk Elephant can’t defend the two red points in the blind spots of the Blind Tigers, so these squares become convenient places for the Lion to give immediate checkmate. The Enhanced Basic Castle, developed by Colin Adams, reduces this problem to only one weak square by swapping the Drunk Elephant and the right-side Blind Tiger. The Enhanced Basic Castle takes an additional move to build, but reducing these key weaknesses by half seems like a reasonable return on that tempo investment.

The bottom-left of Diagram 1 shows the Hanshin Tigers castle, which is also fairly easily formed but requires a greater material investment than the Basic or Enhanced Basic. In this formation, once the Phoenix and Kirin move away, the Blind Tigers are brought together in their place, allowing the Tigers to cover one another’s blind spots. Both Dragon Horses are then brought down over the Golds and backed up by the Silver Generals. A variant of the Hanshin Tigers moves the Silvers up over the Golds instead of the Horses. Either version creates a strong protective barrier, but requires keeping the Dragon Horses or Silvers locked down in defence of the King:

Diagram 3: Hanshin Tigers variations.

This castle comes recommended by the old Lucky Dog Games website. They give as a sample opening sequence for the Hanshin Tigers with Silvers as 1. Ln-6h 2. P-8h 3. P-5h 4. P-7h 5. Ky-7i 6. Ph-8i 7. BT-7k 8. BT5k-6k 9. S-8k 10. S-5k; a similar sequence would work for the Dragon Horse version, just leave the Silvers in place and shift the Dragon Horses one space inward instead.

In the bottom-centre of Diagram 1 you can find the Anaguma Castle. This castle is inspired by the Anaguma Castle of modern Shogi; the name means ‘Bear in the hole’ and it has a reputation as a very strong castle. The Chu Shogi version is certainly strong against frontal attacks, but requires a large material commitment, just like the modern Shogi version. The Anaguma also has the side effect of shifting your King closer to the left side of the board and reducing potential avenues for flight if the castle should collapse. On the positive side, the Anaguma does not tie down your Dragon Kings, which can then join your Free King to contribute to attacks elsewhere on the board.

Finally, in the bottom-right of Diagram 1 we have the Two Dragons formation. In this castle the two Dragon Kings occupy the spaces left by the Kirin and Phoenix once they are moved away. The placement of the Dragon Kings is ideal to support an attack in the centre. Since the powerful long-range pieces tend to be held back in early- and middlegame positions anyway, placing them in the centre of the castle is relatively convenient. However, committing early on to an attack in the centre can be risky — that can leave the wings more open to counter-attack from the opponent. In any case, this particular castle apparently was popular during the Edo Period in Japan, so it may be worth having in your arsenal. If you want to see a historical example of this castle in action, do check out this famous game between Mori and Fukui.

So, what castle should you use? There’s no single answer to this, I think — as in modern Shogi, your choice of defence will depend on the board situation and your own particular style. In a fast-moving, attacking game, the quicker castles like the Basic may be appropriate; whereas in slower, positional games, you may be want to take time to set up a robust defence. In any case, I’d recommend going through Chu Shogi games on Richard’s PBEM Server and observing how strong players adapt their defences to different board situations.

Attacking Principles in the Middlegame

As described in Part I, Chu Shogi is a fundamentally strategic game. The size of the board and of each player’s army means that precise forward calculation of tactical variations is often not practical; instead, aiming for good strategic positions and solid arrangements of your pieces is more important. Generally you will find it very difficult to imagine where your opponent’s piece may end up in 50 moves by just looking ahead move by move, as there are simply too many possible moves on each turn; but if you have a sense for what type of offensive or defensive shape he is going for, then you will be able to place your pieces properly to cope with that.

After the opening, the Chu Shogi board will have some clearly defined battle fronts where each player is attempting to make gains. Each side will have advanced phalanxes of short-range pieces to protect their pawn lines, with long-range pieces on the back ranks providing further support. The Lions will often be placed high in the centre of the board, both sides searching for opportunities to start a Lion invasion of the other’s camp. Both sides will aim to push their attack forward on one of the flanks, cramping their opponent’s defences, and cascades of piece exchanges may happen as one or both sides start attacking.

While going through my collected Chu Shogi materials I found this interesting exemplar early-middlegame position from Shogi Magazine:

Diagram 4: target middlegame position.

This position is by no means meant to be prescriptive — your positions should be constructed in accordance with what the game requires, not any specific target — but it can be useful to look at the key features of this position and why elements of it may be desirable.

First of all, in the diagram we can see that a Basic Castle has been built, albeit in this case with the Phoenix next to the King. The King is flanked by the two Golds, and ready to defend to the front are his Blind Tigers, Drunk Elephant, and Dragon Horses. The Lion is placed high and centrally, in front of the pawn line. Note that every single short-range piece on the back rank has been brought straight to the front lines, backing up the advancing Pawns. The 4th rank is defended by two Side-Movers, and the 3rd by two Rooks. On both flanks we have lined up long-range pieces, backing up the generals on the front line. Note that the Free King, the second-strongest piece on the board, is tucked away safely on 2L; just like the Queen in Chess, it doesn’t pay to bring your Free King out too early!

Now, I’ve no doubt that some choices made in this position would not stand up to current Chu Shogi theory, but nonetheless I believe it’s an instructive example. Leaving aside the specifics, we should be aiming for similar cohesion in our own games and applying appropriate core principles as we aim for a robust post-opening posture:

Bring the King to safety
Keep the Lion centrally placed, restricting the opponent’s Lion and looking for opportunities to invade
Bring the Free King to a safe spot on or near the back ranks
Advance most or all of your short-range generals to the pawn line to press an attack
Use long-range orthogonally-moving pieces to defend the 3rd and 4th ranks — Side-Movers and Rooks are good choices
Position your long-range attacking pieces to defend the advancing generals and Pawns, and drive out the enemy Lion if it attempts to invade

Keeping these principles in mind can help you navigate the opening and develop an early middlegame position that sees you ready to launch a coordinated attack. As you gain experience you will develop a greater sense for the positional requirements of each game situation, and you will get more comfortable experimenting with these principles and finding strategic setups that fit your personal style of attack and defence.

Tips for Specific Pieces

Chu Shogi has a diverse range of pieces at the players’ disposal, and each of them has a role to play in the battles to come. Here are some tips on how to put your soldiers to good use, gathered together from my archive of Chu Shogi materials.

The King: Often the King will stay in the centre of the back rank for most of the game. Try to set up a castle around him and cover the 3rd and 4th ranks to prevent the Lion getting too close too early. If you and your opponent are locked in a mutual mating attack situation, then it can pay to retreat your King toward a safer side of the board, but think carefully about when to spend your moves on a retreat; sometimes the best option is to regain the initiative and counterattack instead.
Pawns/Go-Betweens: In a game with so many powerhouse pieces, it’s easy to forget about the lowly Pawns and Go-Betweens. But both these pieces are essential to Chu Shogi play, and they should never be advanced thoughtlessly. A strong Pawn line backed up by short-range pieces provides an essential barrier against the opposing Lion, and letting your opponent break down that wall could be fatal. As the game develops and you continue to gain space, your Pawns and Go-Betweens can promote as well, so it’s worth carrying Pawns forward with you as you advance.
Phoenix/Kirin: These two pieces have the strongest promotions in the game (Phoenix promotes to Free King, Kirin promotes to Lion), so don’t advance them too early. In the endgame these pieces may have space to advance and promote, so until then keep them well back from the action.
Gold Generals: These pieces have the strongest promotion of any of the Generals (they promote to Rook), so they’re best kept away from the action to leave open that option in the endgame. They’re excellent on defence as part of your castle; in unpromoted form they cover very useful squares in your defensive formation. When the game opens up they can then be advanced if needed to bolster your attacking forces.
Silver Generals: The Silvers are useful attacking pieces, as in Shogi, but in a pinch they work well as defensive pieces too; as you saw above, some castle formations use Silvers to defend the King. Optimal placement and use of the Silvers may depend on what defensive formation you choose to adopt.
Ferocious Leopards/Copper Generals: These pieces should be on the front lines, backing up your Pawns. When advancing your Pawns and attempting to gain space, try to build up numerical superiority with short-range pieces like these. Above all, be patient — hold back on launching an attack until all your short-range generals are in place behind the pawns, and you know you’ll be able to continue pressing your attack even after your opponent starts exchanging pieces to slow you down.
Lances/Reverse Chariots: These pieces can’t move off their file anyway, so I advise keeping it simple: leave them in place defending their edge of the board! Opportunities may arise to promote them in the endgame, but for the most part these pieces tend to stay fairly static unless defending or attacking along the edge of the board, or if promotion opportunities open up later in the game.
Side-Movers: I’ve said this a few times already, so probably you got the message, but the Side-Movers are very important defensive pieces and should generally be patrolling your own 3rd and 4th ranks. An invading Lion is extremely dangerous and with even one supporting piece can probably demolish your castle, but Lions can only step twice on a turn — so with your Side-Movers covering two ranks, your opponent will need to work harder to approach your King with their Lion.
Vertical Movers: These pieces can sit together with your Dragon Kings and other long-range pieces, providing support to your front-line attackers and standing ready to harass the enemy Lion away should it be necessary. Once you gain sufficient space on one side or the other, try to promote your Vertical Mover to a Flying Ox. The Flying Ox is a strong attacking piece and will be a valuable addition to your forces once the board opens up.
Drunk Elephants/Tigers: These are paired together because they are prime defensive pieces — they both can cover 7 of 8 adjacent squares. Blind Tigers are easily moved into a Basic Castle early in the game, and they are very awkward to advance anyway due to being unable to move directly forward, so keeping them on defence is usually the best role for them. The Drunk Elephant should also be kept back to hold the line, but they serve a valuable extra purpose in the endgame. If enough lines open up for the Drunk Elephant to potentially promote, and you’re deep into the endgame, its potential to become a Crown Prince can be very useful. If you do get a Crown Prince, this is insurance against checkmate; even if your opponent succeeds in preventing the promotion, they will have spent valuable time doing so.
Rooks: Along with the Side-Movers, Rooks are key allies in the defence of your King. They can patrol the 3rd and 4th ranks very well, so try to keep these ranks clear so they can readily switch sides depending on your offensive and defensive requirements. As in Chess and Shogi, Rooks can play a valuable attacking role in the endgame, too.
Bishops: The Bishop, like your other long-range pieces, works well sniping from the back of your position and harassing the enemy Lion. Their diagonal movement can often provide opportunities for sneaky discovered attacks — where a move of another piece opens up a line from the Bishop to an opposing piece. On such a large board these opportunities can be easy to miss, so try not to forget your Bishops!
Dragon Horses/Dragon Kings: These pieces are strong ranged attackers, and can work well backing up your attacking generals on the front lines from the safety of the back ranks. As we saw above, both pieces can also strengthen your castle defences if needed or help prosecute a central offensive. In general, don’t be tempted to sacrifice these pieces for short-term positional or material gains — better to build a solid, well-supported attack, winning them the space to eventually promote and become very powerful Soaring Eagles and Horned Falcons. As attractive as those promotions are, don’t rush it; once the board thins out later in the game these pieces can dash across the board and promote pretty easily, and often safely. Rushing them to promotion may just give your opponent chances to gain tempo by harassing them with their long-range pieces.
The Free King: This piece is extremely strong, second only to the mighty Lion. In the early game, keep it far away from the front — a tactical mistake leading to a captured Free King would leave you at a huge disadvantage! Your opponent can also take advantage of a poorly-placed Free King and harass it from range, forcing you to retreat it and lose tempi. In the endgame, let the Free King run wild — its very high mobility is a valuable asset when harrying the enemy King.
The Lion: Your Lion is the most important piece in your army other than the King, but its unique capabilities mean it doesn’t need to hide away in the early game like the Free King. Most players advance the Lion over the Pawns very early in the game, attempting to stake a claim to the centre and probe for weaknesses in the enemy lines. Middlegame Lion invasions are a major feature of Chu Shogi, but don’t be tempted to attempt one too early; without backup your Lion could be easily driven back by your opponent’s long-range pieces, or even forced into a dangerous position if you haven’t opened up enough lines for it. Be aware too that the Lion loses some of its power as the board opens up, since then the opponent has an easier time targeting it with long-range pieces.
In the endgame, the Lion is absolutely devastating. Your goal here should be to advance your Lion as close to the enemy King as possible. To achieve this, bring forward your short-range pieces to interfere with or exchange off your opponent’s defending Side-Movers and Rooks; this will enable your Lion to break through. In combination with long-range pieces pinning down your opponent’s defensive line, Lions can create some spectacular checkmate opportunities once they get in range of the enemy castle. When paired with even a single short-range piece, the Lion can work methodically with it to compromise the enemy’s defenses. If need be, don’t be afraid to sacrifice powerful pieces to force your opponent’s King into the open — in those situations the Lion is often able to achieve a brutal checkmate all on its own!

The Endgame

The endgame is characterised by a much more open board, and this is often where the remaining long-range pieces become very important attacking pieces. Your long-range pieces held in the back ranks can dash forward and promote, and the Lions must advance a bit more carefully given their limited range and susceptibility to attacks from a distance.

To help simplify matters in this stage of the game, look for opportunities to exchange off long-range pieces if you have material superiority. A clever opponent can still mount a stout defence against greater numbers if they have some nimble long-range pieces roaming about the board, so exchanging them off the board so you have the only remaining long-range pieces can be much better for you. Meanwhile, be sure to promote whatever unpromoted pieces you have remaining, assuming you can do so safely, and if you have a Drunk Elephant in a position to become a Prince, try and do so. That leaves you with an extra royal piece which will force your opponent to split their attention.

Remember that Chu Shogi’s endgame is by nature very different from Chess and Shogi, so in certain situations you’ll need to be mindful of some of the special rules of Chu:

No stalemate: In Chess, stalemate — where a King is not in check but has no legal moves — is a draw. In Chu, stalemate is a loss, as there’s no prohibition on moving into check — so the weaker side must do so eventually, and hence loses.
No perpetual check: Repetition is illegal in Chu Shogi, so escaping from a losing situation via perpetual check is impossible.
Bare King loses: Under the Chu Shogi Renmei rules, as soon as one side loses all pieces besides the King or Crown Prince, they lose the game. Often this won’t happen as the losing side will resign first anyway, but in certain situations you may want to take this into account when planning your approach to an endgame with only a few pieces left on the board.

In addition to these differences in rules, Chu Shogi’s unique pieces add many interesting tactical possibilities to the endgame. The super-powered Lion and the late-game appearance of the other Lion Power pieces create some exciting possibilities for pretty checkmates. Probably the best way to get to grips with these possibilities is to try solving some tsumeshogi.

Tsumeshogi

Tsumeshogi are Shogi checkmate puzzles, and are perhaps my favourite Shogi-related activity. I’ve gone to a lot of effort in recent years to acquire tsumeshogi books from Japan, and I never cease to be amazed at the level of artistry in some of these puzzles. Chu Shogi has tsumeshogi too, although of course there aren’t nearly so many of them compared to modern Shogi. Having said that, there are some excellent ones to be found on the Japanese web, including historical 17th-century puzzles from Chu Shogi Renmei available here and here, or some modern creations here.

In this section I’ve picked out a few puzzles that illustrate some of the interesting endgame situations that can occur with Chu Shogi’s unique pieces. As with modern Shogi, solving puzzles like this is hugely helpful for your endgame attack technique, and for increasing your accuracy. The more tsumeshogi you solve, the quicker you’ll be able to spot strong continuations in your own endgames.

Before we start, I’ll summarise the rules of tsumeshogi:

The solver is always Black (moving up the board), and always has the first move.
Black’s King is not on the board in normal tsumeshogi; it’s assumed that Black’s King is going to be mated on the next move if the opponent gets a chance to counterattack.
Due to the above, every move from Black in a tsumeshogi must be check (a forcing move attacking the enemy King).
After each check, White must make the move that most prolongs the mate.
Some tsumeshogi are sou-gyoku tsumeshogi: two-king puzzles, where Black’s King is on the board and gets involved in the mate.
Hisshi tsumeshogi problems have at least one move that is not check.
A well-constructed tsumeshogi problem should have only one solution.

Tsumeshogi for the modern 9×9 game have additional rules relating to pieces in hand and drops, but that’s obviously not relevant here; I do love these kinds of puzzles a great deal, so at some point I’ll try to do a post about the many awesome varieties of tsumeshogi puzzles available for Shogi fans.

Now, below are several Chu tsumeshogi, each more difficult than the last. Try to find the solution by visualising the moves in your head, as you would during a game. Remember that all your moves must be checks (no hisshi puzzles here), and White’s response will always be the reply that keeps them alive the longest. I’ll also put a hint for each puzzle in the caption. The solutions will appear at the bottom of this article.

Hint: Black has both a King and a Prince — use them!

Hint: Free King takes one for the team.

Hint: Find a way to free the Falcon.

Hint: The ultimate sacrifice.

An interesting quirk in the Lion-trading rules

Now, while you’re mulling those problems over, I want to share with you something I discovered while picking which problems to diagram for this post. While searching through shorter problems for an introductory example, I found this puzzle:

At first glance this is a fairly simple three-move puzzle, but the solution turns out to be rather confusing. You can see the solution below; do you notice anything strange about the solution?

The final position has Black’s Lion protected by a Pawn. In theory, at least according to the Lion-trading rules on English Wikipedia, this is not checkmate — White’s Lion can legally take the Pawn, then the Black Lion, and then there’s no longer a threat to the King! But that being the case, why does this Japanese site present this as a correct tsumeshogi?

As it turns out, this specific situation — a non-adjacent Lion protected by a Pawn or a Go-Between alone — is covered by an addition to the Lion-trading rules adopted by Chu Shogi Renmei in 2004. They received a question asking whether the Lion’s double-capture in this situation should be viewed here as a single action, in which case the Pawn cannot be taken, because when viewing the board state as a whole the Lion is both non-adjacent and protected. Alternatively the double-capture could be seen as two separate actions, in which case the Lion can take the Pawn first, then the Lion is adjacent and can be taken freely.

Ultimately, Chu Shogi Renmei adopted the single-move interpretation, meaning that the above puzzle does have a checkmate. The Lion cannot be taken, because it is considered to be protected by the Pawn even though the Pawn could be taken and the Lion would have no further protection afterward.

The reasoning behind this, as I understand it, is that in certain situations ruling the Lion’s double-capture as a double move can lead to contradictions in the trading rules. Let’s use the same puzzle, but just shift the Bishop slightly so it protects the Lion:

So under the two-move interpretation, in this situation White effectively ends up trading away their Lion and only nets a Pawn, which is exactly the sort of thing the trading rules are supposed to prevent. As a consequence Chu Shogi Renmei ruled that we should view the Lion’s proposed double-capture as a single move, so that effectively when the Lion is taken the Pawn is still in place, threatening recapture. That in turn means the double-capture cannot be made, and so in the original puzzle, we do have a checkmate.

At first this seems complicated, but in practical terms it’s just reinforcing the aim of the Lion-trading rules, and ensuring that there are no situations where trading off the Lion for only a Pawn in compensation is allowed. A Lion may still take a Lion one space away protected by a different piece, by taking the protecting piece and then the Lion on the same turn — the protecting piece just cannot be a Pawn or a Go-Between. If you can read Japanese, you can see Chu Shogi Renmei’s discussion of this precise situation here (see Case 4 on that page).

Having learned all this, I felt that using a problem relying on a very specific rules quirk as an introductory puzzle would be far too confusing, and selected the other three-move problem above instead.

Tsumeshogi Solutions

Now then, hopefully you’ve set some time aside and worked out the solutions to the four tsumeshogi above? If so, well done! If not, we’ll go through the solutions so you can see where you went wrong. First, the three-move puzzle:

Since Black has a Crown Prince as well as a King, the King can finish off the other King personally! I was very pleased with this as an introductory Chu puzzle, since the solution highlights the unusual consequences of having an extra King, which is a very new concept if you are more accustomed to modern Shogi or Chess.

Now the five-move puzzle:

Here we have a lovely example of a Lion checkmate, enabled by the valiant sacrifice of the Free King. As mentioned in the endgame section above, sacrificing material to bring the King in range of the Lion often pays off — the Lion can very frequently chase down the enemy King and give mate on its own.

Next, the nine-mover:

For one of the puzzles I wanted to showcase a different Lion Power piece, and in this puzzle we get an instructive example of how the Horned Falcon can very effectively trap the enemy King even in a seemingly well-defended corner. The Falcon’s forward Lion Power allows it to jump or double-capture its way to the King, and conveniently it can also cover both potential escape squares. The setup is nice too — once we figure out that the Horned Falcon can deliver mate in the corner, opening the line to the King for the Whale pops out as an elegant way to drive the King toward his doom.

This puzzle also reinforces a very useful rule of thumb for tsumeshogi — every piece on the board is there for a reason! If a problem could be remade without a given piece and not change the solution, then it’s not a well-constructed problem. So when you’re stuck for a solution, have a think about what every single piece is doing on the board, and see if that shakes loose any clues.

Finally, the mammoth eleven-mover:

Yes, it’s another problem playing with Chu Shogi’s multiple royal pieces, but this one was too good to pass up. Sacrificing a King is an outrageous way to start a checkmating combination! I feel the puzzle would be even a bit more impactful if the King sacrifice came directly before the checkmating move, but even so it’s a fairly jaw-dropping thing to see for a Chess or Shogi player.

From here, I’d suggest checking out the other tsumeshogi I linked earlier, and try some of the other audacious puzzles available to test your Chu instincts to the limit. Solving puzzles like this is a huge help to one’s endgame technique, generally speaking, and some of these puzzles are very cleverly made artistic works, as well. If you eventually become able to solve the really long puzzles lasting a hundred moves or more, you’re well on your way to being an extremely strong Chu player. The real test, however, is whether you can solve the infamous Skyscraper, the longest tsumeshogi ever created, which lasts a staggering 3,257 moves.

For those who can’t read Japanese: you can view the solution to any of the puzzles on the linked sites by selecting it from the drop-down menu on the puzzle’s page, then scroll through the moves using the buttons underneath. There are two rows of buttons; the second row of six is the one you need to use. Going from left to right, the buttons are [Go to first move][Go back ten moves][Go back one move][Go forward one move][Go forward ten moves][Go to last move].

The final installment

The third and final part of my Chu Shogi coverage — for now, at least — will be an annotated Chu Shogi game. I will be presenting a game from the Chu Shogi Renmei website that, to my knowledge, has not been analysed in English before. I’m by no means a master of Chu Shogi, but I know enough to explain the basic ideas behind key moves in the game, so hopefully that will give you a clearer sense of how to evaluate positions in Chu Shogi and how a typical game might flow.

Also, in the near future I’ll be covering Chu Shogi’s big brother: Dai Shogi. My materials for the Dai Shogi introductory article are already almost finished, so this may get posted before the Chu Shogi game. Either way, I hope you’re enjoying my Shogi variant coverage — please do post comments below or send me an email if you have any feedback, corrections, or suggestions.

Tagged Chu Shogi, Games, Shogi Variants, Tsumeshogi

Apr 05 2020

14 Comments

Games, Shogi

Chu Shogi, Part I: How to Play

As some of you out there already know, I’m a huge fan of Shogi, the Japanese version of Chess, and its many variants. Shogi is a dynamic, attacking game enjoyed by millions of players around the world, and in my view is the most exciting of the major Chess variants played today. Chu Shogi is my favourite of the many larger variants of Shogi, and in my estimation is the best-designed game of the lot. I hope that by the end of this very long post you might be inspired to give this unique and fascinating game a try.

I have to admit that, as much as I love Chu Shogi, it is substantially more difficult to learn than modern Shogi or Chess. The board is large — 144 squares, as compared to 64 in Chess or 81 in modern Shogi — and each player starts with 46 pieces in their army. In Chess you need to learn the moves of six different types of pieces, whereas in Chu Shogi there are 28 different moves to remember!

However, once you get a game or two under your belt, all that complexity will melt away — you’ll be surprised how quickly the rules will become second nature. In this post I’m aiming to help you on that journey, by providing a complete reference to all the rules and piece movements you need to know to get started with this fantastic game.

I’ll start first with a brief look at the origins of the game, then I’ll describe the rules in detail, then I’ll show off the moves of all the pieces, and finally I’ll offer some basic tips for new players. Note that given the detailed kanji characters on the pieces and the complexity of some of the diagrams below, I’ve made this post so that each image links directly to a much larger version — please do click through to the larger images if any of the diagrams look a bit cramped on your device.

What is Chu Shogi?

Back in the 14th and 15th centuries, before modern Shogi existed, the Japanese were playing not just one, but three main variations of Shogi: Sho Shogi, Chu Shogi and Dai Shogi. These names mean, respectively, Small Shogi, Middle Shogi, and Large Shogi, and refer to the different board sizes used by each game: Sho Shogi is the direct predecessor to modern Shogi and is played on a 9×9 board; Chu Shogi uses a 12×12 board; and Dai Shogi is played on a 15×15 board. There were many other Shogi variants being developed in Japan around this time, but these three games were by far the most popular.

Chu Shogi is one of the most popular variants of Shogi played today, chiefly because of its finely balanced armies and the dominating presence of the Lion, a spectacularly powerful piece that shapes the entire game. A game of Chu Shogi is substantially more strategically and tactically complex than the smaller Chess-type games we’re used to, and offers the dedicated player limitless variety and challenge. Learning how to coordinate one’s army of 46 pieces on this large board can help us achieve greater strategic heights in our Shogi and Chess games, too.

Thanks to its fantastic play experience, Chu Shogi is the only ancient ancestor of modern Shogi that remains officially alive today. The Chu Shogi Renmei in Japan is the governing body for the game, and there are still regular tournaments happening. Here in the West, Chu Shogi has a small but die-hard following, and many Chu players consider it perhaps the best Chess-type game ever invented (I agree with this assessment). Nowadays Chu Shogi can be played online in real-time or correspondence forms, in domestic and international tournaments (albeit with only a few players), and solo against strong computer opponents. Chu Shogi is more accessible than ever, so why not give it a go?

The Origin of Chu Shogi

Chu Shogi’s immediate ancestor is Dai Shogi, which first appeared in the form of Heian Dai Shogi, a rather ponderous game played with 34 pieces per player on a 13×13 board. This game is first described in the diary of Fujiwara no Yoninaga, a high-ranking general, which was written between 1135 and 1155. Various other diaries throughout the 14th and 15th centuries make reference to Dai Shogi and present it as the most enjoyable form of Shogi, which suggests by this time it had reached its later form of a 15×15 game with 65 pieces per player (which is enormously better than Heian Dai Shogi).

The first reference I’ve found to a much larger form of Shogi comes in a mid-14th century text called Isei Teikin Orai. The book refers cryptically to a form of Shogi with 36 pieces on the board and a ‘dense’ form of Shogi with, apparently, 360 pieces. Unfortunately there are no further details in this book about this mysterious form of large Shogi, although perhaps it is a very early reference to some form of Tai Shogi with its 25×25 board and 354 pieces? Recent research by Professor Tomoyuku Takami proposes that, based on late Heian and Muromachi period documents, the first large Shogi may in fact have been Maka Dai Dai Shogi, which was then reduced in size to form the other large variants including Chu Shogi. More on this to come when I cover Maka Dai Dai Shogi in a future post.

The first detailed presentation of Chu Shogi’s board and rules comes in an Edo Period text titled Shōgi Rokushu no Zushiki (象棋六種之図式), which itself has a tangled history. The book was previously published by 16th-century Shogi craftsman Minase Kanenari as Shogi Zu (Illustrations of Shogi) in 1591, and he said it is a copy of a text he borrowed from a Kyoto Temple that originated in 1443. Allegedly that text is itself a copy of an even more ancient document, but we don’t know anything about that original source.

Below you can see scanned pages of the Shōgi Rokushu no Zushiki that show the Chu Shogi board, promoted pieces, and the movement powers of the pieces:

Thanks to this book we know that Chu Shogi existed in essentially its current form all the way back in 1443, and possibly significantly earlier. There are two other Edo-era sources, the Sho Shogi Zushiki and Shogi Zushiki from the late 17th century, which also describe the rules of Chu Shogi and numerous other variations of Shogi. In most cases they agree on the rules, but some of the very large games have some inconsistencies across these three volumes — more on that when I cover those games in future posts.

Regardless of some of the inconsistencies here and there, Shogi historians generally agree that Chu Shogi was a reduced form of Dai Shogi, which may have been the first large Shogi game or itself derived from larger games. Chu Shogi was then reduced further to Sho Shogi on the 9×9 board, and in the 16th century the drop rule was introduced, giving rise to the modern form of Shogi. Subsequently this rejuvenated version of Sho Shogi became by far the most popular form of the game. Prior to that, Dai Shogi was considered the most prestigious form of Shogi, followed by Chu Shogi, whereas Sho Shogi was thought to be a short and easy game more suitable for children (!).

After modern Shogi took over, Chu Shogi still remained mildly popular all the way into the 20th century. Unfortunately the game suffered a significant drop in popularity following World War II, and even strong support for Chu Shogi from some professional Shogi players failed to revive it to its former glory. In the 1970s and 1980s, an Englishman called George Hodges collaborated with Japanese Shogi scholars to bring Chu Shogi, Dai Shogi, and many other Shogi variants to Western audiences. George Hodges is largely responsible for popularising these games in the West, and he even produced physical sets for large Shogi variants all the way up to the gigantic Tai Shogi. Unfortunately George died in 2010, but his widow Angela Hodges continues producing his Shogi variant sets to this day.

The rules I’ll be presenting here are the rules used by the Japanese Chu Shogi Association, the Chu Shogi Renmei. While these differ in some respects from the rules generally used in the West, particularly in the promotion rules and King-baring rules, the textual evidence we have such as Chu Shogi checkmate puzzles indicates that the Chu Shogi Renmei rules are the same ones used in medieval Japan. For that reason I encourage you to use these rules, as they seem to be historically correct and also have less ambiguity in certain board situations.

The Rules

At the beginning of a Chu Shogi game, each player starts with 46 pieces of 21 different types. The initial board position looks like this:

Diagram 1: Chu Shogi initial position

Just for clarity, for the rest of this post I’ll refer to the two sides as Black and White — Black on the bottom of the board heading up, White at the top heading down. Note that some game records from a long time ago have Black at the top rather than the bottom, but this is always noted somewhere if that’s the case.

Winning the game

As in any Chess variant, the goal of Chu Shogi is to eliminate your opponent’s King. However, unlike Chess, in Chu Shogi you must capture the King, rather than checkmate it — and it’s possible to have two royal pieces at once in Chu Shogi, the King and a Crown Prince. If a player has both a King and a Crown Prince in their army, then the opposing player must capture both of those pieces in order to win.

The nature of Chu Shogi’s win condition means that there’s no stalemate as in Chess, and there’s no prohibition against moving a royal piece into check or checkmate. Obviously this is normally a pretty bad idea.

The Bare King Rule

The Chu Shogi Renmei adopts an additional rule where baring the enemy King is also a win; in other words, if you eliminate an opponent’s entire army except a King or Prince, then you win. However, if your opponent could on their next move bare your King as well, this is a draw, or if they could capture it on the next move, they win instead.

The rule further specifies that any endgame of King + some pieces versus a bare King is a win for the baring side, except when they only have a King + Pawn or King + Go-Between, in which case they have to promote the piece in question first in order to claim the win.

In practice the Bare King Rule isn’t hugely important, as most players would resign anyway as soon as the game seems hopeless, but nevertheless the rule has some interesting consequences for certain endgame situations.

Taking a turn

Once the game starts, Black moves first. The players alternate moving one piece on the board according to the specific movement powers of that piece. If that piece lands on a space occupied by an enemy piece, that piece is captured and permanently removed from the game (there are no modern-Shogi-style drops in Chu Shogi). Pieces cannot capture or move through friendly pieces. If a capture occurs then the move ends at that point — unless the capturing piece has ‘Lion Power’ (explained below), in which case a second capture can be performed. If the captured piece is the opponent’s last remaining royal piece (King or Prince), then the game ends immediately and the capturing player wins.

Normally a player must move a piece somewhere on their turn, but certain pieces with ‘Lion Power’ can ‘move’ without actually changing the board position — this means that player effectively passes their turn. This may be relevant in certain tight endgame situations where not moving can be preferable to moving.

Repeating positions

Sometimes during the course of play, players may enter into a cycle of repeating positions — for example, if a player is threatening their opponent’s King repeatedly with the same piece.

Chu Shogi Renmei’s rules have comprehensive guidelines for dealing with repeated positions:

If the board position is repeating due to one player repeatedly checking the opponent’s King or Prince (placing them under immediate threat of capture), then they must change their move before the 4th repetition of the same position or lose the game.
If one side is repeatedly attacking the opponent’s non-royal pieces during the repetitions, the attacking side must change their move before the 4th repetition of the same position or lose the game.
If the position is repeating due to both players passing using ‘Lion Power’ pieces, then the first player who passed must change their move before the 4th repetition of the same position or lose the game.
If the position is repeating and neither side is attacking, then a draw can be claimed.
In cases not covered specifically by the above rules, then whichever side causes the 4th repetition of a board position will lose the game.

Generally speaking, due to the lack of stalemate and perpetual check thanks to the above rules, draws are rather rare in Chu Shogi.

Promoting pieces

Both players have a promotion zone on the board that consists of the four end rows of the board from their perspective (the rows that contain the bulk of their opponent’s army at the start of the game). So, Black’s promotion zone is rows A through D in the above diagram, and White’s is rows I through L.

If a player advances one of their pieces into their promotion zone, they may choose to promote that piece by flipping it over; the other side will have different characters written in red that show the name of the promoted piece. Promoted pieces are more powerful than the starting version of the piece — often significantly more powerful. Once a piece is promoted, it remains promoted until the end of the game. Promotion happens for each piece only once.

Here’s the starting position of Chu Shogi with all the pieces flipped to show their promoted sides:

Diagram 2: Chu Shogi initial position with pieces flipped to their promoted sides

Note that three of the pieces still have black characters on them — these are the King, Lion and Free King, none of which can promote. I’ve left them in these diagrams just as a reminder of their position in the starting array.

When a piece moves into the promotion zone, promotion is optional — this may sound pointless, but there are situations where promotion may not be advantageous, at least not right away. Some pieces have promoted forms with very different movement abilities, so you may wish to defer promotion if you could make better use out of the original movement pattern.

If you want to promote the piece later after deferring when you first entered the promotion zone, you have to either A) move the piece out of the promotion zone, then re-enter the zone and promote on that move, or B) capture something in the promotion zone.

Note that some pieces that cannot move backward — Pawns and Lances — could theoretically get to the last row on the board and never be able to move again. If an unpromoted Pawn is about to reach the last rank, you can promote it even on a non-capturing move; if any other piece gets stuck unpromoted on the last rank, it just sits there unable to move until it gets captured.

NB: I’m using the Chu Shogi Renmei promotion rules here, which are more strict than the rules on Wikipedia or in the Middle Shogi Manual. In those rules, you can promote any piece after a non-capturing move when already within the promotion zone. However, this makes a lot of Chu Shogi board positions a bit more ambiguous and can cause some rules questions, so I recommend the Chu Shogi Renmei rules.

The Pieces

Remembering all the different moves of the Chu Shogi pieces is a bit challenging at first, but you’ll soon see that there’s a certain logic and pattern to them. The vast majority of pieces can move in a few directions one square at a time, or over any number of squares in some directions, or some combination of the two. A few pieces can jump over some squares, even if those squares contain friendly or enemy pieces. A few others have ‘Lion Power’ and effectively move twice in a turn; this is explained further below.

I’ve made some handy diagrams to illustrate the moves of all the pieces. The diagrams show you the pieces in a rough order, starting from the top row of your army down to the last row. Each piece’s promoted form is shown below its initial form. Remember that the King, Free King and Lion don’t promote.

In the diagrams below, orange squares indicate squares a piece can step to during a move; squares with stars indicate squares pieces can jump to, passing over intervening pieces; arrows indicate directions in which the piece can move an unlimited number of squares; and finally, exclamation marks indicate the piece can perform igui capture on that square (see ‘Lion Power’ below). As always, click each picture to see a massive huge version of the diagrams.

You’ll notice a certain pattern to the distribution of piece movements in the starting position. The back rank contains the King, the Drunk Elephant (both a strong defensive piece and capable of promoting into a royal Crown Prince), and a large crew of short-range Generals. The second and third ranks contain mostly longer-ranged pieces, with the most powerful pieces sitting in front of the King. The fourth rank consists of 12 Pawns, and finally in the fifth rank we have two Go-Betweens, the spearhead of our advancing army.

Note that to help you remember the piece names in full, I’ve used two-character pieces in the above diagrams, but for some subsequent diagrams (and in future Chu Shogi articles) I’ll mostly use abbreviated, one-character pieces to aid visibility. Here is a zoomed-in view of one player’s army with one-character pieces; the first diagram shows the starting position again, and the second has all the pieces flipped to show their promoted sides:

: The starting position for one player, with one-character pieces.

: The starting position with all pieces flipped to show their promoted sides.

For players of modern Shogi, you’ll see that that in general there are many more powerful pieces in Chu Shogi. In Shogi the most powerful pieces are the Dragon King and Dragon Horse; in Chu, you have two of each these on the board at the start of the game, and when they promote they become much more devastating. In Chu you also have the Free King, sometimes called the Queen, which moves as far as it likes in eight directions just like a Chess Queen (but Chu Shogi invented this piece 250 years earlier!). Finally you have the Lion, a piece so flexible, powerful and exciting to use that it inspired me to write a whole article about powerful pieces in Chess variants.

Print versions: I’ve also produced two single-page reference sheets for all the Chu Shogi moves, one version with 2-kanji pieces and another with 1-kanji pieces. The pieces are paired up with their promoted forms and again mostly follow the order of the diagrams below. Hopefully these will help you out if you bring a Chu Shogi set to a games night or your Chess or Shogi club.

: Chu Shogi reference sheet (2-kanji pieces)

Lion Power

To understand how strong the Lion is, you need to understand its special movement rules, referred to as ‘Lion Power’. As you can see in the diagram above, the Lion can jump over one square in any direction, bypassing any friendly or enemy piece on that square. However, it can also do something uniquely powerful — it can perform two single-square moves in any direction in a row, on one turn, and one or both of these moves may be a capture.

This has some interesting side effects — for one, the Lion may appear to capture an adjacent piece without moving, by moving to its square, capturing it, then moving back to its starting square. This is called igui — Japanese for ‘stationary eating’ — and in the diagrams above the squares where igui is possible are marked by exclamation marks in the Lion’s diagram. The Lion may also move to an adjacent empty square and then back, appearing not to move at all; this is how one may ‘pass’ their turn, as mentioned above. Finally, the Lion may capture two pieces in one move.

Here are a couple of examples of the Lion’s unique powers:

Diagram 3: Examples of ‘Lion Power’

As you can see, these powers make the Lion far more flexible and powerful than any other piece on the board. No enemy piece can sit adjacent to it, as it will just be instantly gobbled up igui-style. The Lion can easily escape threats by leaping away or by taking two nimble steps around interposing pieces. Finally, if an opponent leaves multiple pieces undefended, the Lion will eagerly devour them all. So, even without long-range movement abilities, the Lion dominates the board — and when you use it yourself, you’ll see how exciting the game becomes thanks to this magnificent beast.

Lion-trading rules

Chess players out there will be familiar with the Queen trade — when two players mutually agree to simplify the board position by exchanging Queens. In a Queen trade a player will offer their Queen for capture by the other Queen, with their pieces in position to immediately recapture the opposing Queen. The end result is both players lose their Queen but nothing else of consequence, leaving behind a less tactically complex and usually more boring game.

However, the wise inventors of Chu Shogi knew they had a hit on their hands with the Lion, and wanted to discourage players from trading them off to simplify the game. To achieve this they included several anti-trading rules that forbid players from capturing or re-capturing opposing Lions in certain situations. These rules ensure that the Lions often stay on the board for a long time during a typical Chu Shogi game, and that gives this remarkable piece a chance to truly shine.

I’ve created a few diagrams here that summarise the main points of the Lion-trading rules:

Diagram 4: Lion Trading Rules

These rules seem a bit complicated at first, but as you can see in the diagrams above, there’s really just a few points to remember:

A Lion can always capture an adjacent Lion.
A Lion may not capture a non-adjacent Lion protected by an enemy piece — this prevents a mutual Lion trade, where the Lions are off the board but the position doesn’t change much otherwise.
If a non-Lion piece captures a Lion, then the opponent can’t do the same thing on the next turn. This means that if your opponent has just taken your Lion with a non-Lion piece, you can’t take theirs right away, even if it’s unprotected! This prevents trades making use of non-Lion pieces.
A Lion can capture an opposing Lion protected by another piece, but only if it may capture another piece at the same time — and as long as that extra piece is not a Pawn or a Go-Between. This means that if both Lions are going off the board in this kind of position, the Lion that initiates the exchange has to take an additional piece of at least some value with them; again this discourages Lion trades, since trades won’t be possible on even terms.

There are some interesting tactical situations that can arise out of the Lion-trading rules, but don’t worry about those for now — when you’re just starting Chu Shogi, focus on simply exploring the Lion’s capabilities and getting used to these rules. In subsequent posts I’ll talk some more about these rules and how they impact Chu Shogi tactics.

Other pieces with Lion Power

Two other pieces in Chu Shogi have a limited form of Lion Power — the Horned Falcon and the Soaring Eagle. The Horned Falcon can use Lion Power only directly forward — so it may jump two squares forward, or make one or two forward steps, or make an igui capture or a double capture forward. The Soaring Eagle can do the same except on the two forward diagonals only.

The Lion-trading rules do not apply to the Horned Falcon or Soaring Eagle.

Note also that the Kirin (sometimes written Kylin in some Western sources) promotes to a Lion. Once the Kirin promotes to Lion, all Lion Power and Lion-trading rules now apply to that piece.

Beginner Chu Shogi Tips

Chu Shogi can seem daunting at first — just look at all those pieces! — but here I’ll give you a few key tips that can help direct your play in the first few games. I’ll write some additional Chu Shogi articles in the future, including detailed discussion of the opening, middlegame and endgame, and a fully-annotated game (this will take some time — the game I’ve chosen to annotate is 327 moves long!).

For now, here are some key tips for each stage of the game:

The opening

Chu Shogi games are long — expect a typical game to last about 300 moves (compared to an average Chess game at about 80 moves, or a modern Shogi game at about 120 moves). With that in mind, take your time in the opening — Chu Shogi games tend to build gradually, with each player re-arranging their pieces within their own ranks in preparation for launching a coordinated attack. Take your time, follow the tips below and you should be able to keep yourself out of trouble in the opening.

Don’t neglect your short-range pieces! Chu Shogi has a lot of powerful long-range pieces, so it’s easy to forget about your short-range pieces in the back ranks. However, if you advance these pieces early on, they serve a valuable role in protecting your front-line Pawns from an enemy Lion invasion. Later in the game you’ll also have a much easier time promoting these short-range pieces if you’ve already advanced them early, and many of the short-range pieces have useful promotions. Finally, a coordinated march of Generals on the enemy position can enable you to shift the enemy’s long-range pieces into disadvantageous positions, disrupting their attacks or even exposing them to capture.
Set up a solid defence around your King. Even with the many rows of pieces in front of your King, you still should spend extra effort to protect him right from the start of the game. In particular, keep the Drunk Elephant, Blind Tigers and Gold Generals close at hand — all three of these pieces can cover a lot of squares around your King. The Drunk Elephant becomes extra valuable if kept alive in the endgame, since it can promote to a Crown Prince and make your opponent have to capture two royals to win the game. Similarly, the Gold Generals promote to Rooks, which are extremely useful pieces to have around in the endgame when many other long-range pieces may have been swept off the board.
Use your Lion to claim the centre. Jumping the Lion over your Pawn line early on to cover the centre of the board is very useful — it deters the enemy Lion from making opportunistic attacks on your vulnerable Pawns, while threatening to do the same to them. If your opponent starts harassing your Lion with capturing threats, you can easily retreat it back over the Pawn line to safety. The Lion controls a lot of space and is very hard to pin down, so use that to your advantage!

The Middlegame

The middlegame of Chu Shogi starts once both players have developed their short-range pieces behind the Pawns, lined up strong long-range pieces behind them, and are starting to attack the enemy’s position, often along one of the flanks of the board. Succeeding in the middlegame requires strong strategic acumen — tactics are important, but there are so many possible moves on any given turn that it’s often very difficult to anticipate the opponent’s replies to each of your moves. Solid strategic principles can guide you better over the longer term.

Advance methodically. Concentrate your attacking forces along the side of the board where your opponent looks weakest. Back up Pawn advances with your short-range pieces, and keep long-range pieces behind them to snipe at any invading enemy Generals or to deter Lion incursions. Try to keep your pieces moving in lockstep — retreating weak pieces is slow and will lose you time, and time is a key resource in Chu Shogi.
Avoid pointless material losses. At this stage of the game, try to amass your forces on weak points in the enemy camp, allowing for a mass assault later on, rather than impatiently trying to punch through with just a few strong pieces. Early material losses can mount up, and sacrifices can fail to significantly damage your opponent’s defences given the size of each player’s army; whatever hole you’ve punched in the enemy lines with your powerful piece sacrifice will soon be plugged by another piece.
Don’t rush toward promotion. Your short-range pieces will take time to breach enemy lines and hit the promotion zone — don’t rush this, they serve a valuable role in the meantime defending your pawns and discouraging Lion invasions! Your long-range pieces can promote very easily once the board opens up after a few battles break out, so don’t fling them headlong into danger to seek promotion — soon enough you’ll be able to promote your long-range pieces essentially at will. Once you do start to make headway on the enemy position, try to make it a goal to promote a Vertical Mover to a Flying Ox — the Flying Ox is a strong attacking piece.
Keep your Lion centralised and patrolling. Keeping your Lion in the centre will help restrict your opponent’s advance to one flank or the other, and will keep their Lion contained. While managing your own advance, don’t forget to keep an eye out for the enemy Lion, and look for opportunities to drive it away temporarily; this can open up opportunities to make a dent with your short-range pieces, which can then open up lines for your Lion to do some serious damage. Your opponent will be looking to do the same, of course, so don’t let their advancing army set up a beachhead for their Lion!
Don’t forget about defence! While hunting the enemy King and/or Prince, don’t forget to maintain suitable defences around your King position. Many players keep their Side Movers on the third and fourth ranks — this sets up a two-rank barrier that even the Lion finds difficult to cross. Leaving a couple of Rooks behind those pieces provides a further deterrent for invading enemy forces.

The Endgame

The endgame of Chu Shogi is a much more open affair than the middlegame — both players’ defences have given way to some extent, and many pieces have been swept off the board. Long-range pieces are flitting dangerously around the more open board, many more pieces are able to promote safely, and victory might be in sight for one of the players.

Make use of your Gold Generals and Drunk Elephant. Gold Generals can now be advanced in the endgame, preparing to promote to much more dangerous Rooks. Your Drunk Elephant, if needed, can advance into the promotion zone to become a Crown Prince, giving you another bit of insurance in case your King comes under threat.
Advance your Lion on the enemy King. Your Lion is absolutely devastating in the endgame when backed up with some other pieces. Even if your opponent has created a strong defensive castle structure — to be covered in the next article — a few sacrificed pieces can open up holes in that structure that your Lion can exploit. In your hunger for victory, just be careful not to leave your Lion too exposed, or your opponent may harass it away or even capture it!
Take advantage of strong promotions. If you’ve managed to keep your Phoenix and Kirin alive, now’s the time to bring them forward! They move a bit awkwardly, but they promote to Free King and Lion, and having extras of those pieces is always extremely useful. You may also have Horned Falcons and Soaring Eagles or other strong pieces available through promotions, which can do severe damage to your opponent’s remaining defences.

With these basic tips in mind, you should be able to get a handle on the general flow of a Chu Shogi battle once you have a few games under your belt. There’s some good information out there online if you want to take your game further — get in touch with Angela Hodges to buy PDF copies of the Middle Shogi Manual and the back issues of Shogi Magazine, which contain a series of useful articles on the game by R. Wayne Schmittberger. Even if you can’t read Japanese, Google Translating the Chu Shogi Renmei website may be useful — there are a number of instructive articles there, as well as checkmate puzzles and complete game records for both historical and recent high-level matches.

Why should I play Chu Shogi?

You may have looked through this article and thought to yourself — why learn all this? Isn’t this game just a more complicated, slower version of Shogi? Why not just learn Shogi instead, a game with millions of players around the globe?

Ultimately, yes, it’s a complex game, and there’s quite a bit to learn at first. But Chu Shogi offers a very different experience from the typical Chess/Shogi game — whereas those games feel like very abstracted skirmishes between two squadrons of troops, Chu Shogi feels like a war. A strategic approach is vital, because right from the start you’ll be making very consequential decisions about where to concentrate your strength, where and when to attack, and how best to execute your devious plans. All the while, the Lions are stalking the board, scaring other pieces into submission, and offering new tactical situations you can’t find in any game of Chess or Shogi.

Even if you’re not a Chess or Shogi player, I recommend trying Chu Shogi at least once or twice — it’s an incredibly rich game, and could easily turn out to be your ‘lifestyle’ game. If you’re a Chess player, Chu Shogi will be like entering a totally different universe — the balance between tactics and strategy is massively shifted toward strategy, the board is filled with pieces that behave very differently from anything in Chess, and the board is so large that it feels like playing three games of Chess at once. If you’re a Go player — well, Go is hard, so you’ve already got a lot on your plate, but as a fan of a highly strategic game you may find Chu Shogi a particularly compelling take on the Chess genre.

Finally, for you Shogi players, I certainly recommend you keep playing Shogi, as it’s a fantastic game. But playing Chu Shogi can certainly pay dividends for your Shogi game, as well as being extremely good fun on its own terms. If you don’t believe me, then at least you should believe Oyama Yasuharu, legendary Shogi player and 15th Meijin, who was an outspoken advocate for Chu Shogi:

“Ever since I was small I have often played Chu Shogi. My cautious and tenacious Shogi style is probably due to the influence it has had. I believe the reason I think, above all, about improving the cohesion of my pieces, is that I have played Chu Shogi.”

Next steps

So, in closing, I hope this post encourages a few of you out there to give Chu Shogi a try. You can play in live games via the 81Dojo client linked on the Chu Shogi Renmei website, via PBEM on Richard’s PBEM Server or Game Courier, or with physical sets produced by Angela Hodges.

If you’d rather practice against AI opponents, you can play in your web browser via the Dagaz Project — scroll down to ‘Shogi Family’ and you’ll see Chu Shogi, Dai Shogi, and loads of other variants too. If you want a really strong opponent, you can download the WinBoard Shogi Variants Package, which includes HaChu, a computer engine designed specifically to play Chu Shogi (it also plays a mean game of Sho Shogi and Dai Shogi). Apparently HaChu can play a pretty great game of Tenjiku Shogi nowadays too, although this version is not yet released — when it is, you’ll want to download WinBoard Alien Edition to play the larger Shogi variants.

Anyway, please pick one of those options and give Chu Shogi a go — it may take a game or two to sink in, but if nothing else I’m sure you’ll understand how this game managed to survive for 600 years, even in the face of the massive popularity of modern Shogi. You may even find it becomes an all-time favourite, as it has for me.

Even better, once you learn Chu Shogi you can easily pick up the larger Shogi variants — you could learn Dai Shogi in a few minutes, and Tenjiku Shogi in an afternoon. I’ll be covering both these games in later posts, too, including a little piece on why Dai Shogi is more than just Chu Shogi’s older, slower big brother. Tenjiku will speak for itself — that game is like nothing else out there and has a deservedly strong reputation.

In future instalments of this Chu Shogi series I’ll cover more detailed tips for Chu Shogi, including building castles for defense and developing checkmating attacks. I’ll also fully annotate a game of Chu Shogi, talking through the moves and hopefully giving you more insight into the strategic depths this game has to offer.

Tagged Chu Shogi, Dai Shogi, Games, Sho Shogi, Shogi, Shogi Variants

Apr 01 2020

5 Comments

Chess, Games

Powerful pieces in Chess games

In preparation for writing up some detailed articles about my favourite Shogi variants in the future, I spent a bunch of my insomniac hours making Shogi diagrams in Illustrator recently. I thought I might give these a trial run before the main event, so here’s a more off-the-cuff opinion piece of sorts, about the dominant ‘power pieces’ in Chess and Chess-like games.

UPDATE: I hadn’t realised my sources on the Tai Shogi pieces didn’t indicate that the power-pieces in fact have slightly different moves! This then led to the same error popping up in the Long-Nosed Goblin diagram for Dai Dai Shogi. I’ve now updated the diagrams and text to fix the error.

The Queen as a Power Piece

Abstract game designer Christian Freeling, whom I’ve praised extensively in this blog for his invention of Havannah and Starweb, two world-class strategic games, also invented numerous Chess variants over the years. Of particular interest is Grand Chess, an enlarged game on a 10×10 board which includes two additional pieces: the Marshall, which has the combined movement powers of a Rook and a Knight; and the Cardinal, which moves as a Bishop or a Knight. The larger board and larger armies make for a fine game full of strategic and tactical complexity, even more so than standard Chess.

Part of Christian Freeling’s motivation for Grand Chess was his desire to logically ‘complete’ the Chess lineup. He has spoken in the past about the Queen in Chess, the presence of which he calls ‘defendable but arbitrary’, and the lack of other powerful combination pieces:

There are two more combinations, the ‘marshall’ and the ‘cardinal’. They combine the powers of rook & knight and bishop & knight respectively. They should not have been excluded because of an arbitrary boardsize, but they were. Chess became a great game where it should have become an even greater game.

My new pet theory is that the exclusion of these other hybrid pieces has actually been a good thing for Chess — not in terms of rule elegance or logic, but in terms of the play experience, and the subsequent success of Chess games with communities of players. This is not to say that Grand Chess is bad by comparison — far from it, you should definitely give it a try. Though I do think there’s a reason Mad Queen Chess eventually just became standard Chess — the enormous power gap between the Queen and the other major and minor pieces gives the game additional tension, pace and urgency. The Queen is a power piece — a singular, dominant force that gives direction and narrative emphasis to Chess play.

Let’s look at an example of the impact of the Queen in high-level Chess — the famous ‘Gold Coin Game’ between Stefan Levitsky and Frank James Marshall in 1912. Marshall, playing Black, finds himself in this position, with his Queen threatened by capture via Levitsky’s Rook:

23. Rc5 — Black to play.

The next move allegedly ignited so much excitement from the spectators that they tossed gold coins all over the board. Marshall threw his Queen directly into danger with a surprising and deadly manoeuvre:

23… Qg3!!

White resigned immediately. White can’t take the Queen — there’s no variation that works for Levitsky. To give some examples — if White takes with the pawn on h2:

24. hxg3 Ne2#

Immediate checkmate! White is trapped by the Knight and the Rook. If White takes with the Queen:

24. Qxg3 Ne2+ 25. Kh1 Nxg3+

Black immediately gives the same check with the Knight on e2, takes White’s Queen with check, and will take the Rook on the next move. White is down a full Rook and completely doomed. Finally, if White takes with the pawn on f2:

24. fxg3 Ne2+ 25. Kh1 Rxf1#

Forced mate. Black gives check with the Knight again, the King must go to h1 due to Black’s Rook, then that same Rook gives mate on f1. Any other try by White is equally hopeless.

So why is this move so famous? Of course it’s effective, dispatching White in one fell swoop and eliminating any attempts at a defence. The move is certainly hard to find, because long lateral moves are notoriously difficult for even strong players to spot. But we must admit that White was already in trouble here, and it’s not hard to find other, simpler moves that lead to a win as well.

I’d suggest that this move is famous, and by extension all the other notorious Queen sacrifices throughout Chess history, because the Queen is so much more powerful than any other piece that our innate desire is to protect it — the Queen can be a threat from almost anywhere on the board, so every fibre of our being tells us not to throw it away. The Queen is so important that incredible numbers of Chess problems, studies, and books focus on using it, capturing it, and protecting it. The Queen towers over the other pieces, so when someone seemingly goes against all good sense and throws her life away, it’s a thrilling moment. A great Knight sacrifice can be pretty, too, but it doesn’t have the same oomph of a daring Queen sac.

That oomph comes from the Queen’s status as a power piece — a piece that stands alone in each player’s army, capable of dictating the pace and rhythm of the game. Entire games, and indeed tournaments, can rest on the fate of the Queen.

At this point you might say “OK sure — the Queen is badass, I get it. But isn’t that just a quirk of Chess? Is it actually necessary for a great Chess-like game to have power pieces?” I’m willing to concede that a great Chess game may not need a power piece as a prerequisite for being great. But the more I thought about this, the more I noticed that every Chess-like game I play has a piece (sometimes two) vastly more powerful and influential than the others on the board.

Since I know the Shogi family very well, let’s take a look at some of Shogi’s power pieces (note that I won’t be looking at promoted pieces generally, since it would just take more time while making no real difference to the overall pattern). I’m not going to cover every major variant, but a representative slice of six of them — enough to demonstrate that the power piece is not just a fluke of Chess, but a feature common to many games in the King-capture family.

Power Pieces in Shogi

Modern Shogi is well-known for consisting mostly of short-range pieces. Since captured pieces come back to life all the time in Shogi, the game is less chaotic and more balanced thanks to having predominantly short-range pieces. However, Shogi still has the Rook and Bishop — two pieces vastly more powerful than everything else, pieces that can devastate your opponent on their own, or devastate you if you lose one or both of them.

In Chess-like games one way of quantifying piece strength is via exchange values. If we consider the value of a pawn to be 1 point, then we can calculate over many many games the approximate worth of other pieces in terms of pawns. In Chess, for example, Knights and Bishops are worth about 3 pawns, Rooks 5 pawns, and Queens 10 pawns. In modern Shogi we see a similar gap between the power pieces and the rest:

shogi-power-pieces-modern-01

The next-strongest pieces behind the Rook and the Bishop are the Gold and Silver Generals, both worth vastly less. The difference in the mobility of the Rook and Bishop compared to the Generals is particularly striking — on a 9×9 board, with most other pieces being single-step movers or otherwise very constrained, being able to move unlimited distances is seriously powerful.

The Lion in Chu Shogi

Chu Shogi is modern Shogi’s larger ancestor, played on a 12×12 board with 46 pieces per player. Chu Shogi is an incredibly well-balanced game, and widely regarded by its fans (including me) as possibly the greatest Chess game ever invented. Chu Shogi is particularly famous for its incredible power piece, the Lion:

shogi-power-pieces-chu-01

Chu Shogi’s Lion is a slice of pure game design genius. The Lion can move like a King twice in one turn, with all the options that implies — capturing an adjacent piece, then moving back to its starting point (indicated by the ‘!’ in the diagram above); moving any which way in the 5×5 square area around itself, and so on. The Lion can also jump two squares in any direction (indicated by the stars in the diagram). It’s agile, powerful, and adaptable beyond any other piece on the board. The nearest competitor to the Lion is the Queen, which moves exactly like the Queen in Chess (but was invented 300 years earlier); despite the Queen’s massive mobility, it simply can’t compete with the incredible flexibility and brutality of the Lion.

Logically we might think the Lion unbalances the game, but nothing could be further from the truth. In fact the Lion is so enjoyable and challenging to use that the wise inventors of Chu Shogi included special Lion-trading rules, specifically to ensure that players don’t simply trade Lions on even terms early on to simplify the game. The Lion in a sense defines the game — Chu Shogi probably would have faded away like so many other Chess variants, were it not for the Lion.

I want to take a moment here to mention Chu Shogi’s big brother, Dai Shogi. Dai Shogi actually came before Chu Shogi, and includes all the same pieces plus eight more single-step-movers on a 15×15 board (65 pieces per player). Dai Shogi is often cited as Chu’s slower, less exciting predecessor — I personally disagree with this characterisation, for reasons I’ll get into in a future post, but I believe part of the reason for this is the significantly decreased influence of the Lion on the larger board. The Lion is still powerful in Dai, but it no longer drives the game — in fact Dai Shogi does not use any special rules to protect the Lion from exchanges, because of its less central role. This fits as well with my power-piece theory; without the pace and energy of the Lion taking centre stage, Dai Shogi can feel slower, more methodical, and less thrilling than its younger sibling.

Tenjiku Shogi’s Explosive Demons

As we step up to even larger Shogi games, we find that Japan’s ancient game designers were never short of ideas for new power pieces. On larger boards individual pieces have less influence in general, so to construct power pieces on that scale you have to really get crazy with it. Fortunately they were up to the challenge. Tenjiku Shogi is a massive game played on a 16×16 board with 78 pieces per player, and yet again we have a clear standout power piece even on this massive field of battle:

shogi-power-pieces-tenjiku-01

Yes, you are reading that correctly — the Fire Demon in Tenjiku Shogi is worth 83 pawns. The Fire Demon is also one of the most powerful Chess pieces ever invented. This beast can move as far as it likes in six directions, or step any which way in a 7×7 square around itself — and whichever way it moves, once it stops every enemy piece adjacent to it is removed from the board. If the opponent moves a piece next to the Fire Demon on their turn, that piece gets burned away too.

So instead of Tenjiku Shogi being a bigger, slower version of Chu, the Fire Demon turns it into a sort of supercharged extended edition. Pieces die violently and in large numbers, and games can be over in surprisingly short amounts of time. Note that the next two most powerful pieces in the game, the Great General and Vice General, are also staggeringly strong, able to jump over any number of friendly or opposing pieces in order to perform a capture. Even with that significant power these pieces still are only half as strong as the mighty Fire Demon. Like the Lion and the Chess Queen, the Fire Demon is in a class by itself.

Dai Dai Shogi’s Hook Movers

Dai Dai Shogi — literally translated that means ‘Big Big Shogi’ — is an extremely sizeable game, played on a 17×17 board with 96 pieces per player. Once again the sheer enormity of the board didn’t deter our intrepid designers from producing yet another power piece:

shogi-power-pieces-dai dai-updated-01

Our friend the Lion is back, but this time as only the third-most powerful piece on the board. Towering above him are the hook-moving pieces; these monsters can move as far as they like in one direction as a Rook or Bishop, then turn 90 degrees and do it again, all in one turn (although they may only capture once). In the case of the Hook Mover — worth a ridiculous 114 pawns — that means on an empty board it can reach any square in a single move. That single piece is considered to be worth more than five Lions.

R. Wayne Schmittberger in a 1981 issue of Shogi Magazine had this to say about the power of the Long-Nosed Goblins and Hook Movers in Dai Dai Shogi:

The dominant piece in the middle game is the Long-Nosed Goblin, and in the endgame the supremely powerful Hook Mover, which not only attacks every square on an empty board but gives double-check by itself!! This makes interposition against it impossible in many cases. Generally a game will end quickly if a player is able to get the deadly combination of a Hook Mover and a Furious Fiend near the enemy King, where they will simply run amok and eventually combine for an elegant tsume [mate].

This power piece isn’t just a random addition, it’s carefully integrated into the fabric of the game. Dai Dai Shogi is notable for having a very asymmetric initial position; there are 64 different types of pieces in each player’s 96-piece starting army. The Hook-Mover and the Long-Nosed Goblin are tucked snugly away in the back ranks, waiting to be unleashed when the board is open and starting to empty of other pieces — precisely when they’re at their deadliest. As R. Wayne Schmittberger says, the middle- and endgame of Dai Dai Shogi is heavily influenced by these pieces, and the tactical complexities they introduce alongside the huge menagerie of different pieces gives the game a unique flavour. Thanks to this tactical and strategic richness, Dai Dai Shogi stands out even in the crazy world of Shogi variants.

Hook Movers in Maka Dai Dai Shogi

Next up is Maka Dai Dai Shogi, one of my favourite Shogi variants. Maka Dai Dai is an immense game, played on a 19×19 board with 96 pieces per player, and is notable for its strange pieces named after mythical spirits, and for the fact that the King promotes into the near-omnipotent Emperor that can jump instantly to anywhere on the board. Even on this larger board, the Hook Mover still works perfectly as a power piece:

shogi-power-pieces-maka dai dai-01

Once again the Hook Mover towers over the rest, worth more than double its nearest competitor. The Buddhist Spirit, which moves as both a Lion and a Queen and has special rules that make it essentially immortal, still pales in comparison. In fairness, one could say in this case that the ultimate power piece in Maka Dai Dai Shogi is the Emperor, which is so unbelievably strong that the entire game changes completely when a King promotes. But the Emperor doesn’t always appear, while the Hook Mover is always lurking, ready to cause trouble — so in that sense I consider the Hook Mover the real power piece here, because it always will impact on the game.

Tai Shogi: on the biggest boards, mobility is King

Our last stop on the Large Shogi Express is Tai Shogi, a monstrosity of a game played on a 25×25 board with 177 pieces per player. Here once again the Hook Movers reign supreme, and in practice are even more powerful with the extra room to manoeuvre on such a gargantuan board:

shogi-power-pieces-tai-updated-01

In Tai Shogi all the strongest pieces are hook-movers of some description, but the double-Rook Hook Mover still rules the roost, and it’s not a close competition. On this massive board rich with weak targets, the Hook Mover’s value jumps up to a preposterous 232 pawns, well over twice the value of its double-Bishop brethren.

Note that the Capricorn and Long-Nosed Goblin have slightly different piece values; the Long-Nosed Goblin is able to move one square orthogonally, as well as having the double-Bishop move, so it is slightly more powerful. This option to spend a turn to switch diagonals means the Goblin can actually reach every square on the board, instead of half the squares. However, spending a whole turn on this when you have 177 pieces to move is rather costly, so this does not create a huge difference in piece value. Also, the Capricorn promotes to Gold General, whereas the Long-Nosed Goblin does not promote; since the Capricorn’s promotion is actually a demotion, this means it has to be used more cautiously. That being said, before demotion the Capricorn remains a deadly threat and incredibly mobile.

R. Wayne Schmittberger, noted Shogi variant expert, underlines the importance of the hook-moving pieces in all these titanically large games:

Tai Shogi is the ultimate marathon game in the Chess family. In terms of the number of pieces and playing time, Tai Shogi is to Dai Dai Shogi what Dai Dai Shogi is to Chu Shogi. A serious game will require several long playing sessions to complete and will usually require more than 1,000 moves per player. Like Dai Dai and Maka Dai Dai, Tai has hook-moving pieces that dominate the board in much the same way that a Lion does in Chu Shogi.

Tori Shogi’s Menagerie

Now to allay any fears that only huge and ridiculous Chess-type games fit my theory, let’s take a moment to look at Shogi’s elegant little sibling, Tori Shogi:

shogi-power-pieces-tori-01

Tori Shogi is a diminutive game, particularly in comparison to the others we just looked at — the board is only 7×7, and each player starts with a mere 16 pieces. Yet even here we see a similar dynamic — only one piece, the Eagle (a promoted Falcon), has unlimited movement range of any kind. As a result, the Falcon’s value is nearly double that of its ancestor. Granted, in this case the Eagle isn’t present from the start, but the action in Tori Shogi is frenetic enough and the Eagle powerful enough that it often has a strong influence on the game.

Stepping away from Shogi for a moment, we can see that the same properties appear in other popular Chess games too — like Xiangqi and Janggi (Chinese and Korean Chess, respectively), where the Chariot is about twice as strong as its nearest competitor (the Cannon):

Janggi-Xiangqi-power-pieces-01

Xiangqi is frequently cited as the most popular traditional board game in the world, and Janggi has a robust professional scene in Korea and a growing international player base, so once again we see that power-piece Chess games tend to attract a robust following. Incidentally, both these games are very different from Chess and Shogi, and well worth your time — I’ll be discussing them in detail in future posts.

I admit that my knowledge of Chess variants is by no means encyclopaedic, but I argue that the prevalence of power pieces in notable Chess variants suggests that the seemingly unbalanced starting setup of many games in this family is actually an asset, not a weakness. The Chess variants that have survived the centuries and retain a following today seem to share a predilection for the power piece.

I can certainly understand that having a single dominant piece type might strike a game designer’s mind as distasteful, but from the perspective of the player, power pieces give these games an exciting dynamic. In the case of the large Shogi games, they stay playable and interesting largely because of these power pieces — without them, these games would drag on forever, and with so many slow-moving targets plodding around there’d be far fewer thrills in any particular capture or sneaky tactical sequence. But a nuclear Fire Demon sacrifice destroying eight pieces in one go? Yes, please!

So, in contrast to Christian’s view, I’d say that Chess and its many cousins has achieved cultural-icon status partially because the starting position is illogical and lopsided in its distribution of power amongst the pieces. The ubiquity and popularity of the power piece across the games profiled here suggests that this dynamic appeals to players across the centuries and across cultures, and that it translates equally well to large and small boards and starting arrays.

Mitrofanov’s Deflection

Before I leave you, I want to showcase another famous Queen sacrifice in Chess. This example comes from an endgame study. Chess endgame studies are carefully composed endgame problems where one side must win or draw, and a properly-composed study must have one, and only one, correct solution.

This particular problem was composed by Leopold Mitrofanov at an endgame study competition in 1967. The problem opens with Black pushed into a corner, but armed with two Knights and a Bishop, and threatening to promote a pawn any second:

White to play and win.

White can win here, presumably via one of those pawns on the right side of the board. However, those pawns are less advanced than Black’s, so the first question for White is: how to delay that dangerous pawn? First, White can push back the opposing King by pushing the b-pawn, then offer a Rook sacrifice:

1. b7+ Ka8 2. Re1!

Black must take the Rook to get his pawn through, which gives White a chance to sneak in an advance of the g-pawn. Both sides end up promoting their pawns to Queen shortly thereafter, and Black retreats the Bishop to protect the King:

2… Nxe1 3. g7 h1=Q 4. g8=Q+ Bb8

Now things get a bit heated. First, White pushes the a-pawn, cramping Black’s King, and Black retaliates with a Knight check. White takes the Knight, but then Black’s Queen jumps into the action and takes White’s h-pawn:

5. a7 Nc6+ 6. dxc6 Qxh5+

This looks really bad for White! Black’s King is protected in the corner, the White Queen is off in the other corner, and Black’s Queen now has free reign to chase down White’s King. There’s nowhere for the King to go.

Luckily there’s another option other than a King move:

7. Qg5!!

Outrageous. White plants the Queen directly in front of Black’s Queen, blocking the check — but then Black can take it for free, and White’s in check again! What’s the point?

The point is to deflect the Black Queen. Black must take the Queen, and in so doing takes his own Queen off a key diagonal. Now when White retreats his King to a6, Black can’t immediately give check:

7… Qxg5+ 8. Ka6

Suddenly, Black is in terrible trouble! His Knight is out of play on the bottom of the board, and the Queen has the White King trapped but can’t do anything with it. White, despite having only a few pawns left, has the upper hand. Black captures the a-pawn with his Bishop, hoping to whittle down the advancing horde, then sacrifices his own Queen to draw the King away from the defence of the pawns:

8… Bxa7 9. c7 Qa5+

Unfortunately these desperate tactics lead nowhere. Black’s Knight is useless, and his King can’t capture both pawns at once, so one promotes to Queen:

10. Kxa5 Kb7 11. bxa7 Kxa7 12. c8=Q (1-0)

It’s over! White has a Queen and Black is completely out of options. White can easily drive Black’s King into the corner and force mate in a couple of moves.

Mitrofanov’s ingenious study has all the hallmarks of a classic — a clever solution, a glorious and counterintuitive Queen sacrifice, and a Rook sacrifice too. No wonder it’s been called ‘the study of the millenium’. For me, it’s another example of the powerful psychological impact of the Queen sacrifice; the winning move 7. Qg5!! strikes us as so absurd that the solution seems even more creative and beautiful.

Tagged Chess, Chu Shogi, Dai Dai Shogi, Dai Shogi, Games, Grand Chess, Janggi, Maka Dai Dai Shogi, Shogi, Tai Shogi, Tenjiku Shogi, Tori Shogi, Xiangqi

Mar 27 2020

Connection Games VIII, Part I: ConHex

UPDATE 27 Oct 2021 — Fixed the images for the extended ConHex boards (they were missing corner spaces), and removed the links and images of the Nestor Games ConHex boards, which are sadly no longer available.

ConHex is a unique connection game invented by Michail Antonow in 2002. You may remember that Hex was inspired by Piet Hein’s interest in the four-colour problem, which is related to map-colouring; ConHex makes this inspiration much more explicit.

In ConHex, players compete to claim the corners of spaces on the board until they gain control of half or more on a given space, at which point that space becomes their colour. The first player to connect their colour’s sides of the board with coloured-in spaces is the winner. The ConHex board has 41 spaces consisting of a mix of rectangles and hexagons, with 69 playable nodes:

The standard ConHex board, as depicted on Little Golem

ConHex games tend to twist and writhe their way across the whole board, covering much more of the available space than the average connection game. While there’s a definite lean toward tactics over strategy on the standard-size board, there’s still plenty of intricacy on offer, as we can see in this sample final position:

Red wins this game after 52 moves, having connected the two red sides of the board.

How to play ConHex

ConHex offers an interesting twist on the usual pure-placement connection game vibe by adding the additional sub-game of claiming nodes to conquer board spaces. Rather than simply claiming a space with a stone, a player must vie for control of every space; this adds some intriguing tactics to the game. In effect, you’re playing the game on two layers: the node-claiming ‘undergame’, and the connection game ‘overgame’ as spaces are gradually claimed.

Here’s how to play:

Two players, Blue and Red in this formulation, vie to be the first to connect the sides of the board marked with their colour with an unbroken chain of spaces under their control.
Blue makes the first move; the swap/pie rule is in effect for the first move of the game.
Players take it in turns to place one counter of their colour on any unclaimed node on the board. One placed, nodes are never moved and cannot be removed.
If, by placing a node, a player has claimed half of the nodes connected to any adjacent space, then those spaces are then under the control of that player, and a marker piece of their colour is placed with that space. Once claimed for a given colour a space remains that colour for the rest of the game.
Note that not all spaces on the board have the same number of nodes: edge and corner spaces require 2 out of 3 nodes to be claimed for that space to be claimed by a player; hexagonal and rectangular spaces elsewhere require 3 out of 6 nodes to be claimed; and the central square requires 3 out of 5 nodes to be claimed.
The first player to connect the two sides of the board marked in their colour with claimed spaces wins the game. Draws are impossible in ConHex.

Here’s some examples of how claiming nodes leads to claiming spaces:

conhex-diagram 1-01

Note that claiming a single node can influence several spaces, and lead to claiming more than one space in a single move:

conhex-diagram 2-01

Tips for beginners

ConHex packs a lot of action into a small space, and the first few plays can feel daunting as you get into pitched battles over every space on the board. Here are some basic tips to help you get started and get a feel for the game:

Especially in the early game, spread your influence around the board. Remember that each node influences three neighbouring cells, so try to claim nodes so that you maximise your impact on those cells. If a neighbouring cell is already claimed by the opponent, think about grabbing a different node that influences still-open cells.
Don’t be a prisoner to your plan! Once you and your opponent have staked claims around different parts of the board and tactical battles start kicking off, you may find that your initial strategic plan starts to fall apart. Don’t panic — try to find alternative paths to connect your nodes. There’s no shame in abandoning your carefully-prepared plan if another path has more promise! Try to prepare for this possibility early — if you follow (1) above, a nice wide territory can afford you multiple possible paths of connection if one doesn’t end up resolving in your favour.
Use forcing moves to gain tempo. In turn-based games, when you force your opponent to forget whatever they wanted to do and respond to your move instead, that’s called gaining tempo — gaining time. In ConHex, the edge and corner cells can be claimed with only two nodes, so these cells can be a good resource for forcing a response from your opponent. If they see you advancing scarily along the side of the board, they will feel the need to intervene, giving you an opportunity to attack elsewhere and gain the initiative. You’ll see examples of this in the annotated game below.

Phil Bordelon, creator of the Caeth/Noc/Noeth meta-rules that will be the focus of the second part of this entry in the series, sent me some great strategic tips that should help any budding ConHex (or Caeth/Noc/Noeth) player:

Defend at a distance. Nodes have a surprisingly large influence on the board in this game, so when your opponent threatens to advance, try to interpose yourself at a distance between them and their connective goal. Defending directly on cells where your opponent already holds an advantage just lets them gain tempo while not actually containing their advance.
Don’t be afraid to mix it up. Cells will eventually need resolving as the game goes on, and while you will want to spread your influence wide across the board, you also want to pressure your opponent to commit themselves. Getting involved in tactical fights will clarify the board situation and push your opponent to reveal their plan, so don’t be afraid to get in there.
Don’t forget the goal. While resolving cells, remember that the ultimate goal of the game is connection, not just winning control of cells. If your opponent is threatening cells that you don’t need, let them! While they’re rejoicing over their new territory, you can be building methodically toward your connective goal.

Note that there’s some tension between these goals — you can’t just claim influence, or fight local battles, you need to balance these elements throughout the game. Cells can’t be won without tactics, but without a strong connective framework there won’t be anything to fight for in the first place! These tensions between strategic goals and complex local fights are what make ConHex — and Phil’s meta-games — really interesting.

Annotated Game — Jos Dekker vs mmKALLL

To give you a peek at the strategy and tactics of ConHex, let’s take a look at a game between two high-rated players on Little Golem. This particular game was played between Jos Dekker and mmKALLL, and was quite a back-and-forth contest that lasted 49 moves, which is quite a long haul when you consider the small size of the standard ConHex board.

A quick note on notation: I’ll be using move notation as on Little Golem, where specific nodes are identified by the letter of the appropriate file and the number of the appropriate rank, as indicated below — but I’ve elected not to leave the notation on the subsequent diagrams, because I couldn’t find an aesthetically pleasing board/font combo:

conhex-notation

With that out of the way, let’s pick up the game after four opening moves:

Position after 1. I2 2. H7 3. D7 4. E4

Blue opens in the bottom-right with 1. I2, and in subsequent moves both players stake claims around the centre of the board. Note that since the edge and corner cells in ConHex require just two nodes to claim rather than three, and the centre cell requires 3 nodes but has lower connectivity than the hexagonal cells, in this game there’s a better balance between central and corner/edge cells than in other connection games.

Note too that while each node may not feel like a big move, each node in fact influences three neighbouring cells. With that in mind you should try to claim nodes that influence as many cells as possible — claiming nodes on spaces already claimed by the opponent is potentially wasting an opportunity to exert more influence elsewhere.

Position after 5. I7 6. I5 7. J5 8. J4

In the next little sequence, Blue seizes the initiative and jumps in behind Red with 5. I7. Red would prefer Blue not hold several cells along the edge where Red needs to establish a connection, so this leads to Red responding as Blue marches closer to the lower-right…

Position after 9. J3

…Sadly this leads to Blue claiming two cells at once in the corner, thanks to Blue’s earlier opening move at I2. This already makes Red’s life a bit more difficult. Red does have a node advantage on the two rectangles between the centre and the right side, but Blue now has an annoying foothold in the corner.

Position after 10. I10 11. E9 12. G8 13. C5 14. C2 15. D3 16. F2 17. B3 18. A1

Red responds with due caution by claiming a node at the top-right corner, to make absolutely sure Blue cannot block off the whole right side. Blue responds by starting a framework of nodes cascading down the left side, while Red bolsters their strength in the centre, eventually running all the way down to the bottom-left corner and claiming it.

The stage appears to be set for the coming battle: Blue appears poised to attempt to cut across the board diagonally across the centre, while Red perhaps will look to connect the top-right and bottom-left corners.

Position after 19. E2 20. D2 21. F3 22. G2

Blue now immediately starts a battle along the bottom edge, building on the earlier node at D3, claiming a new cell and pushing Red to commit to more nodes along the edge. Red appears stronger down here, but Blue remains in a position to claim the two other spaces incident to D3.

Position after 23. I8 24. H9

Before pursuing that advantage, however, Blue jumps north toward Red’s upper-right corner, forcing them to respond at H9 to avoid further Blue cells getting in the way of Red’s plan to connect across the centre.

Position after 25. G3 26. D5 27. C4

Now Blue jumps back south, evening up the score 2-2 on a second rectangle along the bottom edge. Red responds in kind with 26. D5, forcing Blue finally to claim the two lower-left cells with 27. C4.

Position after 28. C7 29. C6

Red again jumps into a Blue-majority cell with 28. C7, and again Blue responds by taking two cells in one with 29. C6. After these tactical scuffles, Blue appears more robust for the time being, with seven cells claimed compared to Red’s four. But Red may still try to move north from the southern edge, and retains control of the upper-right corner.

Position after 30. H3 31. H5 32. G4

Indeed Red does push northward, curling around Blue’s outpost of five squares in the lower-left quadrant of the board. Red is threatening to connect to the upper-right corner — a play at H6 or I6 would do the trick, but Blue can defend.

Position after 33. H6 34. E8 35. F8 36. D9

Blue of course spots this threat and responds at H6 without hesitation, preventing the north-south connection for Red. Red then moves to shore up their defences, claiming a cell just above Blue’s lower-left cluster to make their job a bit tougher, and threatening to connect horizontally to the upper-right corner.

Position after 37. F9 38. F7 39. E6

Blue responds by blocking the possible Red claim with 37. F9, and Red begins to move toward the centre. Blue’s response at E6 leaves Red’s upper-left cell somewhat isolated. Clearly at some point a battle will rage over these last few central cells….

Position after 40. E10 41. G10 42. J7 43. J6

For now, though, Red jumps north to attempt to bring their upper-left cell back into the game, and to constrain Blue’s options. If Blue wants to connect their rightward cells to the central and leftward ones, they will need to either snake through the centre or sneak around Red’s upper-right corner, but Red still holds an advantage there. Red follows this up with 42. J7, which forces Blue to respond at J6; Blue may now hold two more cells around J6, but Red remains strong in the corner and is now ahead one node in cell incident to J7. Blue’s only path to connection is now through the centre of the board.

Position after 44. F4 45. G6

Red now makes a move on the centre first, claiming two central cells with 44. F4 and building on their chain of cells leading from the lower-left corner. Blue moves in as well with 45. G6, and now the central cell finally comes into play.

Position after 46. F6 and 47. F5

Blue however is a tempo ahead in the centre, so Red’s attempt to claim is immediately short-circuited by 47. F5. Blue is now connected from the bottom-right corner all the way through the centre, and is only two cells away from a winning connection to the northern edge.

Position after 48. F10 49. H10 (1-0)

Red makes a last-ditch effort to get in the way with a play at F10, but Blue simply claims two cells at once with H10 and wins immediately.

So there we have it — a good example, I think, of what an exciting game of ConHex looks like. By the end the players had fought for dominance in nearly every part of the board, and each individual node caused a cascade of tactical complications.

Super-Sized ConHex

As you can see, ConHex manages to pack quite a lot of excitement into a small board, but as you probably have noticed by now I’m a fan of playing on larger boards in general. As it turns out, several people expressed a desire for larger ConHex boards on BoardGameGeek too, so I jumped at the chance to construct these monsters (also available in PDF):

: ConHex+1

: ConHex+2

: ConHex+3

: ConHex+4

: ConHex+5

Click on the images to retrieve larger images of these boards, if you prefer that to the PDFs at the BGG link. To give you a sense of scale — if you print ConHex+5 so that each node is 22mm in diameter (same size as a standard Go stone), you’ll need a mat about 77cm on a side (a bit over 30 inches). Soon I’ll be adding black and white versions of the boards to the filepage as well, in case you do prefer to use Go stones.

Each of the plusses represents an additional outer ring of perimeter cells. I’ve maintained the basic geometry of the regular board, so the edge and corner cells are still quicker to claim, but offer less connective options than central cells.

If you do try using any of these, please let me know whether you enjoyed the experience! I’d like to find out which board sizes lead to greater strategic sophistication without making the play experience too overwhelmingly complicated.

Playing ConHex online

ConHex is fairly well-known, as far as connection games go, so there are several good options for online play. Compared to some of the more obscure connection games you should be more than able to find some opponents.

For correspondence play, Little Golem of course is popular — in fact all my diagrams and expanded boards here are based on their version of the ConHex board, which I find the most visually appealing and practical. Richard’s PBEM Server is another popular place to play, and ConHex can be played using the server’s graphical web interface.

For real-time play, I’d recommend igGameCenter. This site is usually pretty active, and if you jump into the chat on the main page you can normally find someone willing to play their large selection of connection games. Yucata.de is another option — I haven’t personally used this site before, but the ConHex page shows a number of players who’ve played hundreds of games of ConHex, so presumably finding an opponent wouldn’t be too difficult!

I should note that as far as I can tell, every site uses the standard board only — I seem to be the only oddball who created some larger ones. However if anyone out there wants to try playing on the larger board(s), do give me a shout!

Buying ConHex

If you prefer physical games over virtual, luckily ConHex is one of the relatively small number of connection games popular enough to actually have been published in official form. The game was published for the first time in 2005 and has been continuously available ever since, including in this gorgeous wooden edition by Gerhards Spiel und Design:

conhex-kugeln-aus-halbedelstein-light

The origins of ConHex

According to Cameron Browne in Connection Games: Variations on a Theme, ConHex is derived from Michail Antonow’s earlier game called Pula. Pula is played on a hexhex-4 board — I’ve mocked up a quick example below — where players claim vertices of the hexagons in order to claim spaces, as in ConHex. Rather than aiming for connection across the board, however, players simply vie to control the most hexagons on the board.

Pula

Apparently Antonow also developed a follow-up game called Pula 2, where players instead aim to gain the most points according to this scoring system:

1 point for connecting adjacent sides of the board with a chain of hexagons in their colour
3 points for connecting non-adjacent sides
5 points for connecting opposite sides

Pula 2 sounds like it might be quite interesting — I’m generally a fan of point-scoring connection games, and the multiple possible connection types could lead to some complex tactical considerations. However I expect it would shine more on a somewhat larger board than hexhex-4.

More importantly, what Pula shows us is that the vertex-claiming mechanic of ConHex is actually pretty flexible — it can function very well in other games too. Lucky for us, Phil Bordelon independently discovered this fact in 2004 and invented the Caeth and Noc meta-rules — rules that can be used to modify nearly any connection game. In Noc games, players claim spaces by claiming vertices as in ConHex, whereas in Caeth games players claim edges of spaces. Fifteen years later he also gave us Noeth, where players have to claim a half of the vertices and the edges of a space in order to claim it — and the 12* move protocol is used as well. With these meta-rules, any connection game can gain an additional ‘undergame’ like we see in ConHex — and Phil’s rules significantly extend the undergame concept.

In part II of this post, and in collaboration with Phil, I’ll focus on these meta-rules and discuss how they can inject some new life into our favourite connection games.

Tagged Caeth/Noc/Noeth, ConHex, Connection Games, Games, Michail Antonow, Phil Bordelon

Mar 22 2020

3 Comments

Games

Connection Games VII: Onyx

Today I’m going to talk about a game with a highly unique visual presentation and capture mechanism: Onyx. I’m really fascinated by this game, which is helpful, because making all the boards and diagrams for this post took a lot of time!

Onyx was published by Larry Back in the year 2000 in Abstract Games Magazine Issue 4. The board geometry immediately stands out — the game takes place on the intersections of an Archimedean tiling of squares and triangles (well, technically all triangles but the squares are important in this game):

onyx-12x12-plain-dots

: A 16×16 Onyx board. A suitable setting for a deeply strategic contest.

: 20×20 Onyx board, generously implemented by the Gorrion server after I made this board. Very challenging!

Besides being immediately visually interesting, this board tiling creates interesting variations in connectivity for different points on the board. The intersections at the centres of the squares are relatively weaker points, as they only connect to four adjacent points — but as we shall see, playing at these weaker points is sometimes essential.

How to play Onyx

Onyx is part of the relatively small portion of the connection games family that includes a capture mechanic, whereby enemy pieces can be removed from the board. The capture rules are unique and need some explanation via diagrams, so first I’ll cover the basic rules and then explain capture in detail.

The basics:

Two players, Black and White, compete to form connections across the surface of the Onyx board. Black must form an unbroken chain of pieces connecting the top and bottom edges of the board; White must form an unbroken line of pieces connecting the left and right edges of the board. Intersections at the corners of the board are considered part of both sides to which they are connected. Draws are not possible in Onyx
Before the game starts, the players can choose whether to play the standard variation, where four White pieces and four Black pieces are placed on the marked points of the appropriate colour at the start of the game. In the open variation, the game board starts empty. (Note: both variations are very playable; the standard variation has the advantage of increasing the importance of the sides and corners of the board during the game).
Black moves first, placing a single stone on any empty intersection of the board. The swap rule is in effect for the first move of the game, so the second player may either swap and take Black, after which the first player is now White and plays a White stone in response, or the second player may stay as White and play a White stone.
Each turn, a player may place one stone of their chosen colour on any empty intersection of the board. However, a piece may not be placed on the intersection in the centre of a square if any pieces are already placed on the corners of that square.
Once placed, stones may not be moved. Pieces can be removed from the board via capture (explained below). Captured pieces are removed and returned to the player of that colour. Points on the board vacated by captured pieces are free to be played on subsequently by either player.

Here’s a completed game of Onyx won by Black. The pieces highlighted in red show the winning vertical connection:

onyx-12x12-sample-game-1 -completed

Capturing Rules

Capturing in Onyx is about forming a particular pattern. Basically, if on your turn you are able to complete a pattern in which a square area on the board has two of your pieces at diagonally adjacent corners, and two of your opponent’s pieces on the other diagonally adjacent corners, and the centre point of the square is unoccupied, then your opponent’s pieces on that square are captured:

Here White places a piece on the corner of the square, which completes the capturing pattern. The two Black pieces are captured and removed from the board.

Double-capture is also possible, if a single move leads to the completion of this capturing pattern on two squares at once:

In a double-capture White places a piece at the intersection of two squares, and manages to complete the capturing pattern on both squares simultaneously. All four Black pieces are then removed from the board!

The capturing mechanic in Onyx leads to some interesting consequences. Recall that you may only place a piece at the centre point of a square when no pieces have yet been placed on the corners. This means that capture can be prevented, but requires you to place a piece on a weaker point. The possibility of capture also prevents a player from easily blocking the other on the diagonals, and prevents deadlocks in general from grinding the game to a halt.

You might notice that after a capture, the captured player can immediately threaten a re-capture by placing a piece on one of the newly-emptied corner points. As a result you’ll often see a sequence like this:

White starts the sequence by capturing. Black responds by making a re-capture threat on one of the vacant points. Finally, White ends the threat by placing a stone on the remaining empty point — now no more captures can happen on this square.

Making connections in Onyx

Given the unique board geometry and the capturing mechanism in this game, there are some novel types of connections that you don’t see in other connection games. I will summarise some key connection types and show some examples of sequences of play that can result.

Onyx has a basic connection between pieces that is the equivalent of the bridge in Hex — the diamond, a simple but strong connection where any attempt by the opponent to break it can be answered easily:

Here White establishes a diamond connection. Black’s attempt to break it is easily answered on the other empty point of the diamond.

Less secure than the diamond is the square — an attempt to break this connection can result in a secure connection as seen below, but a clever opponent might find a way to divert your attention elsewhere and capture your two pieces instead.

White establishes a square connection. Black attempts to cut across the diagonal, but White answers by filling the last remaining corner.

Next up is the house, which is very secure. There is no threat of a capture here, so only a deadly double-threat forcing a response elsewhere on the board can allow this connection to be broken.

White builds a house. Black’s anaemic attempt to break it is easily countered by playing on the remaining empty point.

Unusually, Onyx has a connection that benefits from the presence of an opposing stone. Larry Back calls this a duplex, because it resembles a house containing two different families. In isolation this connection can be secure, but the presence of the opposing piece makes it a bit easier for the opponent to generate threats that require a response outside the duplex formation. If the threat of a cut is stopped by a capture, the opponent can also threaten recapture, which gives another opportunity to generate threats elsewhere.

White builds a duplex. Black attempts to cut, but that simply leads to a capture by White and a complete connection (for the moment).

Most importantly we have the long diamond connection. This connection initially looks precarious — there’s a long distance between the connected pieces. However, the long diamond is actually quite strong:

White forms a long diamond connection. Black attempts to block a connection, but that leads to a capture by White.

However, here we see an instance where playing on the weak point at the centre of the square pays off. Black can break the long diamond connection, but at the cost of three moves, one of which is on the weak centre point:

Black successfully breaks the long diamond connection with a play to the centre of the square. White has no way through.

The long diamond can also be used defensively. If a player plays their stone at the end of what could be their opponent’s long diamond connection, this is called an opposition long diamond. Here’s an example of how the opposition long diamond can be effective, assuming White attempts to bludgeon their way through directly rather than playing around the obstruction:

Black plays an opposition long diamond formation. White attempts to push through, but Black can simply capture.

This is a very simplistic continuation — for more sophisticated discussion of the opposition long diamond, please see Larry Back’s article in Abstract Games Issue 11.

The long diamond connection is a very important part of Onyx. Understanding this connection allows you both to play these connections effectively and to block them. Given that the long diamond allows connections to grow more quickly across the board, it’s very important to know how to deal with them.

Tips for playing Onyx

Bearing in mind I’m very much a beginner in this game, from my reading and my early experiences getting absolutely ruined by Larry Back on the Gorrion Server I can offer a few tips that might help you get started.

Know your connections! Get familiar with the basic types of connections outlined above. Play around with different attempts to make or break connections in these formations. The more comfortable you are with these basic connections, the more quickly you’ll be able to recognise effective moves in a given board position.
Don’t ignore the sides and the corners. Particularly in the standard variation, where pieces are placed in the centres of the board edges at the start of the game, pay attention to the sides and corners of the board. Playing in the centre is valuable too, but if you don’t take care of the sides and corners, your opponent can get a lethal head-start on a strong connection along the side of the board. In the early game, balance your plays in the centre with plays in the corners (but not too deep in the corners).
Don’t forget — your own stones can be a liability! Unlike in games like Hex or Y, where having extra stones around is never bad for you, in Onyx carelessly-placed stones can help your opponent. As we saw above, the strong duplex connection can be formed using an opponent’s stone! A badly-placed stone might also hurt your later attempts to connect stones by opening you up to a capture. Try to avoid placements that open up tactical advantages for your opponent! Conversely, if you can force your opponent to play a move that weakens their position — say, by giving you an opportunity to build a duplex — then go for it.
Watch the diagonals! Like in other connection games, in Onyx you can end up in ladder formations, where both players are matching each other move-for-move as they make their way across the board. In Onyx these ladders have been dubbed snakes by designer Larry Back, and look like this:

A typical snake formation. Both players are writhing their way across the board, playing solely along opposing edges of the squares to avoid the possibility of a capture.

Because of the possibility of a snake forming, and the dire consequences if your opponent gains an advantage in these situations, it’s important to pay attention to the development of play along crucial diagonals on the board. Don’t just let your opponent set up shop along the diagonals!

Again these are very basic tips, but if you keep these ideas in mind while playing you can at least find some semi-sensible moves to play and get a feel for how the game works. After working with these basic ideas for awhile, do check out Larry Back’s articles in Abstract Games — particularly the tactical tips in Issue 6 and the deeply-annotated sample 12×12 game in Issue 11. Those articles go into much more detail on the concepts I’ve mentioned here.

From there, Larry’s article in Abstract Games 17 about edge templates will be valuable for the advanced player. Edge play is complex in this game, and knowledge of these template positions will give you critical insight in these moments, where sometimes only one move will allow you to connect or to block your opponent.

Sample 16×16 game

Since Larry Back already annotated a 12×12 Onyx game in Abstract Games magazine issue 11 at a much deeper level than I could, I thought I’d do a quick walkthrough here of a 16×16 game. Right from the start let me say that this is just my reading of the game — I’m sure I’m missing things here. But, as with learning Go, reviewing games and trying to understand why moves were played is a great way to improve, so hopefully any future game reviews I do will get better over time!

Like other connection games, Onyx is highly scalable, and larger boards can be used to provide a greater strategic challenge. The 16×16 game seems to have a nice balance between depth and game length — games are complex and interesting, but don’t wear out their welcome. You can play 16×16 and 20×20 Onyx online at the Gorrion Game Server, or you can print out my PDF boards (16×16 and 20×20) and play face-to-face.

The game below was played on the Gorrion Server between the server’s founder, dashstofsk (playing Black) and larry_back (the game’s inventor, playing White). Let’s pick things up 8 moves in:

Position after 1. C6 (swap) 2. E12 3. K11 4. L5 5. H8 6. F4 7. H4 8. H9

This game is using the standard variation, in which Black and White start with four pieces each on the sides of the board. Initially Larry opened with C6 in the lower-left corner, but dashstofsk elected to swap, so from this point on Larry played White.

In the opening phase here you can see both players staking out territory. Black has laid claim to the lower-left and upper-right corners, while White is camping out in the upper-left and lower-right. Note that all four of White’s pieces are sitting precisely on the board’s main diagonals!

Position after 9. K8 10. J7 11. I8 12. I9 13. N10 14. J9 15. J8 16. L12 17. F12 18. K12

Ten moves later, both sides have built up a bit of a wall in the centre of the board — some structure is starting to develop now after the opening. Black has cut off any of White’s ambitions to connect J7 and J9, and at the end of this sequence White has blocked Black from venturing north from K11. Still plenty to play for at this stage.

Position after 19. G12 20. G10 21. M12 22. L11 23. N11 24. M8 25. K9 26. LM910

After 26 moves, both sides are starting to probe their opponent’s defences. Black’s initial extension at G12 is promptly stifled by White forming a diamond at G10. White follows up by venturing south from L11, further complicating Black’s hopes of heading north. At the end of this sequence both sides have overlapping long diamonds over the square spanning the L and M files and the 9th and 10th ranks; White spends a move playing on the centre of that square, aiming to block Black from connecting their long diamond and securing a connection vertically for themselves. From here Black needs to consider starting a new adventure elsewhere on the board.

A note about move notation — the central intersections in the squares on the board are actually located between the rank and file designations around the edges of the board. However, we can identify a central point by the ranks and files covered by the square in question — so in this case, we can notate White’s move 26 as LM910. For future reference, moves that lead to a capture are followed by an asterisk, and a double capture by two asterisks.

Position after 27. I11 28. J12 29. J11 30. I12 31. H11 32. E15 33. FG1516 34. F15 35. G15 36. G14 37. I14 38. G13

Following the last exchange, Black gamely heads west, eventually building a diamond connection to G12 with 31. H11. Seeing no more profit to be made here, White suddenly jumps north, forming a long diamond with 32. E15 — but Black quickly responds by playing at the centre, blocking off the long diamond. White, undeterred, veers south and links G13 to I12 with a duplex connection. White now has a dangerous-looking chain stretching all the way from E15 to M8.

Position after 39. O5 40. O4 41. N5 42. N4 43. L7 44. M4 45. M6 46. OP67

Seeing the danger, Black attempts to regain the initiative with 39. O5, starting a new front against the right edge of the board. White quickly jumps in to block any attempts to connect further south, and after a few more exchanges White has a strong wall keeping Black hemmed in. This culminates in White spending a move disrupting Black’s long diamond between O5 and P8.

So far Black’s attempts to make progress along this edge are not bearing much fruit.

Position after 47. N7 48. F5 49. G4 50. E1 51. G2 52. G5 53. I5 54. I4

Black plays a final move along the right edge here, building a house with 47. N7, which also prevents White from forming a diamond at the same point and potentially making something useful out of the stone at OP67. Sensing again that a change in focus is needed, White jumps over to the lower-left corner with 48. F5.

After a few more moves, Black has formed a second house connecting G2, F4 and G4, which also prevents a diamond from White between H1 and G2. White remains resourceful, however, and jumps sideways with 54. I4, forming a duplex with the stones at G5 and G4 and reaching over toward his line of stones starting at L5. We can see now that White’s opening moves are paying off here — by having some stones placed early in key corners along critical diagonals, he’s ensured he would have some options at this later stage in the game. If Black had full control of this corner, White would not have much counterplay here and would need to start fresh elsewhere.

Position after 55. L4 56. K5 57. K4 58. K7 59. L8 60. I6

Things are starting to get a bit desperate for Black. White extends the line of stones on the lower-right with 56. L4, then jumps north with 58. K7, with a threat to punch through Black’s line of stones and connect to M8. Black responds swiftly, closing that door with 59. L8.

But White’s response at 60. I6 looks strong — with that one move, he forms another duplex connection between G5, I5 and I6, and threatens to connect to the line of stones at K5. Black’s interposing stone at I5 is an annoyance, but now White appears to have two possible paths around it.

Position after 61. D5 62. E5 63. C7 64. E4 65. A3 66. C4 67. AB45 68. B6

Black sees White is attempting to complete his chain across the 4th and 5th ranks, and mounts a defence with 61. D5, forming a diamond connection with C6. White responds by strengthening his chain with 62. E5. Black seems to anticipate a move northwards and blocks at C7, but that leaves White the opportunity to connect at E4. Black attempts to wall off the edge with 65. A3 and 65. AB45, but White’s responses at C4 and B6 seal with deal. White now has an unstoppable connection to the left edge from B6, a duplex connection from there to C4, an unstoppable connection to the right edge from O4, and two ways around the interposing stone at I5. Black sees the writing on the wall and resigns.

If they’d played to the end, we might have seen a final position something like this:

Position after a possible continuation 69. A6 70. A5 71. B5 72. C5* 73. B5 74. C6 75. J5 76. K6 77. P5 78. P4 79. H6 80. H5, White wins

I’m not going to pretend my hypothetical continuation here is by any means best play in this situation, but I think we can be reasonably confident that there was not too much Black could do here. White has enough options for connection at each key point in the chain to fend off Black’s defensive tries. Ultimately I think White’s strong opening, securing key points along the main diagonals, and later the deft manoeuvring near the lower-left edge and around the Black stone at I5 secured the win. With that clear path through the centre and all the way to the left edge, White ends up with a completed connection between A5 and P4.

Hopefully this sample game gives you some idea how an Onyx game feels in play. On the 16×16 board I think the game really shines; more strategic options open up, play often bounces around disparate parts of the board, and yet each move still feels consequential. My currently ongoing 20×20 game with Larry is, to my knowledge, the first one ever played, so I’ll reserve judgment on that board size until we at least finish one game! If pressed, I’d probably say it seems interesting thus far, but definitely too large for a beginning player like me to have much of a chance against Larry. Nevertheless I’m enjoying myself.

Next steps

As mentioned above, if you want to play Onyx I recommend the Gorrion Server, which offers 12×12, 16×16 and 20×20 boards, all with either the standard variation or the open variation. The web interface also allows you to play out moves for both sides on the board to check variations, which is very convenient. The server needs more players, so please join us!

Alternatively, you can play Onyx on Richard’s PBEM Server — however, here you can only play 12×12 (standard or open variation).

To learn more about the game, your best port of call is definitely Larry Back’s articles in Abstract Games magazine. He offers basic tactical advice, annotated games, and puzzles to sharpen your tactical vision. Other than that we don’t have much more strategic advice out there — so please come play with us online, and help us discover more about what this fascinating game has to offer!

I’m not 100% sure what I’ll feature next in this series — at the moment I’m leaning toward covering ConHex and Phil Bordelon’s related meta-rules. At some point as well I’ll cover Gonnect, then circle back to cover Christian Freeling’s two predecessors to Starweb, YvY and Superstar. He apparently doesn’t like either of those games very much anymore, but I’m interested in the various descendants of Star so I’d like to write up something on these games.

Thanks for reading — if you know of a connection game that might fit my tastes that I haven’t mentioned, do get in touch and I’ll investigate it and write about it further down the line. Part of my motivation for doing all of this is to open my mind up to new games, so I’m very happy to take suggestions!

Tagged Connection Games, Games, Gorrion Server, Larry Back, Onyx

Mar 19 2020

1 Comment

Games

Connection Games Part VI: Twixt

As promised, today we’re going to take a look at TwixT — a classic connection game designed by Alex Randolph in 1962. Twixt (I’m giving up on the second capitalised ‘T’ because I’m just going to keep forgetting it anyway) is one of the relatively rare connection games that actually was released in physical form — and copies are still readily available via Ebay and used board game sites. I have a copy of the 1962 3M bookshelf edition, which looks like this:

twixt-pic2

twixt-pic4

The game is played on a 24×24 square pegboard, and each player is armed with 50 pegs of their colour — Red or Black — and 50 bridges that span between those pegs, as in the photo above. Each player strives to complete a continuous path of linked pegs reaching connecting their sides of the board.

So far, so similar, right? But what sets Twixt apart is that, despite the seemingly enormous size of the board, games resolve quickly — and fiercely. Twixt is a highly tactical game — David Bush estimates that the game is about 80% tactics on the standard-size board — and the tactics are razor-sharp. By that I mean a single mistake can be very costly in this game, and sometimes what constitutes a mistake isn’t immediately obvious.

The upshot of this is that Twixt rewards careful play, deep calculation of possible continuations of each move, and substantive study of tactical principles. It’s a tense and exciting game, and in my opinion one well worth learning. I can’t possibly cover all of the myriad complexities of Twixt in one post, of course, and I’m only a beginner myself, but luckily 3-time Mind Sports Olympiad Champion David Bush has helped me tremendously by providing general tactical tips — with examples! — and a fully-annotated game on a small board.

We’ll start with the rules and an overview first, then we’ll move on to tactics, and finally the annotated game.

The Rules of Twixt

Like the other connection games we’ve covered, Twixt is quite easy to learn. This is how it works:

The Red player plays first. After Red makes their first move, Black may invoke the swap/pie rule on that move only — if Black chooses to swap, they are now Red, and Red now becomes Black and makes Black’s first move. Alternatively, players may swap and keep their initial colours by reflecting the opening move across the main diagonal and replacing the peg with a Black one, then playing on from there.
Each turn, players may do the following:
1. Remove as many of your own links from the board as you like — usually not necessary, but sometimes helpful to clear up the play area somewhat.
2. Place one peg of your own colour in any vacant hole on the board, except your opponent’s border rows (the single rows behind the lines of your opponent’s colour, as seen in the picture above).
3. Place as many legal links of your own colour as you like. A legal link is available when two pegs are one ‘knight’s move’ apart — in other words, they are at opposite corners of a 2×3 six-peg rectangle. No links may cross each other.
The first player to connect the sides of the board marked in their colour with an unbroken chain of links wins the game. If neither player is able to do this, the game is a draw. Draws are very uncommon in Twixt, generally speaking.
Players of different skill levels may elect to play a handicap game, in which the stronger player concedes a starting advantage to the weaker one. The smallest handicap, for use between two players rather close together in strength, would be to allow the weaker player to take the first move while denying the stronger player the option to invoke the swap/pie rule. From there, players may elect to use row handicapping — here the weaker player’s two sides are moved closer together by removing some rows from the board, making their task easier. In these games the weaker player is always Red and always plays first.

Note that the annotated game from David is a row-handicapping game, which will nicely show off this excellent feature of Twixt. Relatively few connection games have straightforward options for handicapping between players of disparate ability; Twixt’s row handicapping makes these kinds of matches just as tense and exciting as any other! Row-handicapping is supported in real-time Twixt play on igGameCenter, too.

Another nice property of Twixt that it shares with most connection games is its scalability. The default board is of course the 24×24 pegboard shown above, but the game plays well on both smaller and larger boards (within reason). Little Golem has recently added options for play on 30×30 and 48×48 boards, and as with other games like Hex, larger board sizes add extra strategic wrinkles to a game of Twixt. For a very detailed preview of 30×30 Twixt, do take a look at this deeply annotated game by David Bush on BoardGameGeek. David says this about 30×30:

In a standard game, a player might make four or five moves, usually in the opening, which are based mainly on intuition. The rest of the game is spent attempting to tactically justify the plan you are now stuck with. A larger grid allows a much greater variety in the shape of your strategical plan, and offers a better balance between intuition and calculation.

Having said that, for the beginning player, it may be worth starting first at a smaller size — say 18×18, or a handicap game with a stronger player — before graduating to standard 24×24, then think about trying games on larger grids once you become well-acquainted with the standard board.

As has become my custom in this series lately, I’m going to show you a few final positions of some Twixt games below so you can get an idea how a game might look. First, let’s take a look at a 24×24 game from Richard’s PBEM Server:

twixt-sample-24-1708

In this game Red resigned after 41 moves, and we can clearly see why — Black has a continuous, unbroken connection across nearly the entirety of the board, and will easily finish a complete connection within a few moves. Red made a fairly scattershot attempt to block Black’s progress, but ultimately Black was undeterred and deftly slithered straight across the middle of the board.

Here’s another 24×24 game, this time a more intense tactical battle:

twixt-sample-24-1487

This time Red resigned after 57 moves — this is quite long for a Twixt game! Clearly both sides made several abortive attempts to get a strong connection going, and the battle raged across most of the board. Ultimately Black was able to find some order amongst the chaos, building up the circuitous connection we see at the bottom of the board. Red sensibly threw in the towel at this point, as by this point Black has a stronger connection as well as numerous ways to stymie any attempts by Red to get something going.

Let’s take a quick look at one more 24×24 game — this one was played on Little Golem between David Bush and a strong AI called TwixtBot. This game was played at a very high level, far beyond my ability to talk about sensibly, but you can take a look at some detailed analysis of this game on its entry at the Twixt Commentator website.

twixt-sample24-twixtbotvDB

Twixtbot is playing White — Little Golem uses White and Black instead of Red and Black –while David is playing Black. Black resigned here on the 50th move of the game (White’s last move is highlighted in red). Again I’m not able to analyse this game in detail, but you can see that despite Black’s hold on the centre of the board, White has been able to cut off Black on the left and prepare the ground for a connection along that edge of the board. I recommend taking a look at the game via the link to Twixt Commentator above — when you step through the moves one by one, and click through the variations in the comments as well, you can get a taste of how intricate Twixt tactics can be at high levels of play.

Finally, since I’ve already linked you through to David’s deep commentary on a 30×30 game, I’ll briefly show off a sample game at 48×48. Now, 48×48 games are long, and not commonly played, and this particular game has nearly an 800-point rating difference between the two players, but nevertheless you can get an impression of how challenging games at this size will be:

twixt-sample48-2

White was the player with the sizeable rating advantage, and in the end Black resigned after 72 moves. White clearly had the upper hand here from the beginning, and lived up to their rating by methodically winding their way through Black’s defences. 48×48 has yet to achieve the growing following we see for 30×30, but I hope at some point it does take off a bit more — I’d be fascinated to see what pitched battles between strong players would look like on this enormous playing area.

Twixt Tips for Beginning Players

Now I’m going to turn things over to David Bush, who has kindly offered up some useful core principles for new Twixt players:

The ONLY way to win is to block your opponent on the whole board. More so than with most other pure connection games, there is a difference between making a nice pattern for yourself and blocking your opponent. The latter should always take priority.
Play lightly. Just because you put some pieces on the board does not mean you have to use them in your final winning path. Be ready to start a new path if the opportunity arises.
Focus on tactics. Try our hand at these interactive puzzles which can occur in a real game. In my opinion Twixt is at least 80% tactics.
NEVER play Twixt before breakfast.

Let’s take a bit of a deeper look at some of these points. Note that these examples below are quite sophisticated, and perhaps challenging for a new player. I recommend following along with some helpful Twixt software like JTwixt (needs Java to run), which will allow you to place moves on the board and try possible alternate variations, or T1j (also needs Java), which is less full-featured when it comes to analysing games but includes a computer opponent to try your moves against.

The Only Way to Win is to Block

Here is a typical opening position:

must_block1

Black has just played i14. In the game, Blue answered with K11.

must_block2

This 3-3 relationship with H8 is called a tilt setup — Blue can make a single move that connects these pegs in two different ways. This is all well and good, but it’s too slow for Twixt. Black played N16.

must_block3

This 5-2 relationship with i14 would take two moves to complete a connection, but such a connection can form in a variety of ways. You can see the network of possible linking paths is like a diagram of a cube. This is a very resilient pattern. It is difficult for Blue to find a way to attack through that gap. Blue tries to block on the right with P16.

must_block4

You can see that P16 is on a line that leads to W2. Black could start a race toward the upper-right corner with P15 — a ladder chase — but Blue could simply follow that line to W2 and win the chase. But Black N12 is much stronger.

must_block5

Black has a commanding advantage here. Instead of K11, blue might have played O13.

must_block6

This is not as well connected to H8 as K11 was, but that’s not as important as stopping black from achieving an easy win through the middle of the board. Blue has threats now to connect O13 to the top and to the bottom. This is a much more balanced position.

Play Lightly

This position is from a game between two versions of a Twixt bot. The bots are crushing heads these days. At least one human is probably still stronger as of Spring 2020.

play_lightly0

Black abandons its pegs at F4 and L5 to start a new battle along the bottom. A couple moves later we get this:

play_lightly1

To a player with some experience, S21 looks doomed. But that’s the point. S21 is a feint, a threat that blue has to respond to. As blue keeps adding pegs to the bottom right, black will improve its connection to the left, and then switch to an attack elsewhere along the right edge. Here is the game several moves later:

play_lightly2

Blue’s group in the bottom right is almost useless. Black gave up pegs at F4, L5, and S21 for the sake of gaining an overall advantage across the board.

Here’s a more typical example. Note that the blue borders are on the left and right here.

play_lightly3

This 4-1 blocking pattern between i6 and E7 is often the best way to conduct a corner battle. Black is willing to abandon the i8 group in some variations, in order to gain an attack down the left edge. A few moves later we get:

play_lightly4

For black, a win via E16 is just as valid as a win via J11.

Hopefully you could follow along with David’s examples here — as you can see, Twixt has a steep learning curve due to the sharp tactics involved, but the end result is a game with dynamic and exciting play.

Annotated Game — Zurround vs David Bush

This is a handicap game on a small grid, annotated by David Bush. Red (Zurround) has to connect across 17 rows; Blue (David) has 18 columns to deal with.

A quick note on the move notation — for each move, we simply write the location of where the new peg was placed on the grid. Since links are generally added automatically in most Twixt online clients or software you might use, it’s normally not necessary to specify which ones are added. On occasion though you may need to change links around depending on the server — Game Center for example — so in those cases, if you need to understand the notation there is a quick guide on the page of interactive Twixt puzzles.

1. H9 2. H13

3. M11

M11 is an excellent way for red to press his advantage. It makes many threats to connect to the top and to the bottom.

4. L8

5. J10 6. H5

Blue is forced to open up a new front, but he may be able to use H13 later.

7. J6 8. K12

9. L13 10. M5

11. L7 12. N7

13. i4 14. J9

Blue threatens to punch through along the top, at i7, or along the bottom, at L10. Red might be tempted here to play J8 which is a double linking move. But this does not answer both threats that blue is making.

handicap03a

I said that blue was threatening L10, and he is, but it would be a mistake to play there immediately.

handicap03b

Here red can win with H14.

handicap03c

Red threatens to double link at i12. We look at three variations here. The first is i11 G12 G10 F10:

handicap03c1

The second is i15 G12 G14 F14:

handicap03c2

and the third is G15 i12 i14 J14:

handicap03c3

So, instead of L10, blue should play at L14.

handicap03d

This is better than L10 because it still makes two threats to connect to the right, L10 or N13, and guards against red’s H14 threat. We will see how later in the game continuation. We return to the position after blue J9.

handicap03

In order to win here, red needs to play the same sort of trick that blue played with L14 in the previous variation. Blue used the space available on the bottom right. Red needs to use the space available on the left.

15. F8

handicap03e

Very good move. Red covers both of blue’s threats with a single move. The F8 group threatens to connect to the top in two ways, and to the bottom in two ways.

16. L14

Red could have won here with F13.

handicap04a

One possible continuation is i7 F4 F12 E11:

handicap04b

It almost looks like blue could do a “pincer attack” here with E8. But it doesn’t quite work after E8 D7 G9 E9:

handicap04c

Returning to the game:

17. H14 18. G15

Now blue is winning.

19. i12 20. i14

21. C14 22. D12

23. N14

Red sets a trap. If 24. L10:

25. i14 26. K15 27. L15

But blue sidesteps the trap.

24. M16

25. D11 26. E10

27.Resign

Next steps

From here, I suggest getting out there and playing some games! After gaining some experience and putting these tips to the test, a good way to continue learning would be to check out David’s articles in Abstract Games magazine — in Issue 2, he provides the rules and a deeply-annotated game; in Issue 4, he covers basic tactical concepts and setups; and in Issue 7 he covers more details on how to battle for dominance in the corners.

There are several good options for playing Twixt online. Probably chief among these is Little Golem, a correspondence game server which houses a dedicated Twixt community full of strong players, and the site supports the 30×30 and 48×48 variants as well. Every game has a link next to it to enable you to analyse it on the Twixt Commentator website, which is also a convenient feature.

Note that Little Golem uses the TwixtPP rule set; PP stands for ‘pen and paper’, and these rules are actually the original rules for Twixt before the physical sets were produced. In TwixtPP, your own legal links are placed automatically after each move by the server and are never deleted, and your links can cross over each other — but note that crossed links do not count as connected! In practice, these minor rule differences don’t have a huge impact on play, but there are some rare situations where they do change things somewhat, so keep an eye out for those.

Also, this serves as a helpful reminder that you can play Twixt using pen and paper! Just download and print some boards on a sheet of paper and draw your pegs and links using different-coloured pens or pencils. This is a great way to try out the game without investing in a set.

You can also play Twixt on Richard’s PBEM Server — you’ll need to read the various FAQs and such to get started, but once you get past that you can play games graphically via the web interface. This server supports games up to 40×40, and row handicaps of up to 18 rows. Here the rules are those of the physical game, not Twixt PP; however, the server does automatically place legal links for you, which is helpful.

If you’d rather play Twixt in real time, igGameCenter is a great option, as mentioned above. GameCenter supports row-handicapping as well, which is great for new players — David and I have played a few handicap games there and they were profoundly educational. The board by default is drawn in a rather tiny resolution, but pressing Ctrl and +/-allows you to change the display size. You can step back through your games afterward by clicking around in the move list, though analysing games in detail is probably best done by entering the moves into JTwixt on your own. On the whole it’s a great place to play real-time games.

Summing Up

So that, in a nutshell, is Twixt. I’m very much a newcomer to the game, and faced a trial-by-fire in my first matches by facing David right off the bat! However, our games were not only educational, but also showed me that Twixt is challenging, filled with tension, and clearly can be a ‘lifestyle game’ just like Chess, Go, Havannah, or Hex. I highly recommend trying it — the steep learning curve means it may not be for everyone, but if it is for you, there is a tonne of depth for you to discover and enjoy.

In future posts I’ll be covering some other interesting connection games with some unusual qualities: Onyx, a connection game played on an Archimedean tiling with captures; Gonnect, a connection game played using the rules of Go; and Slither, a recent invention combining placement and movement to generate shifting, snakelike connections across the board. I’ll also be covering ConHex and the related meta-rules — rules that can modify almost any connection game — invented by Phil Bordelon. Please look forward to those!

Tagged Connection Games, David Bush, Games, Twixt

Mar 12 2020

4 Comments

Games, Uncategorized

Connection Games V: Side Stitch

We’re back looking at connection games again, and this time we’re going to cover a game invented in 2017 by Craig Duncan — Side Stitch. Side Stitch is a game reminiscent of Star and *Star, where players must make connections between groups touching key cells along the edges of the board. Where Side Stitch differs from its predecessors is that it incorporates a recursive group-scoring mechanism that ensures there are no draws, rather than using a scoring penalty to encourage the formation of larger connected groups as in Star and *Star.

How to play Side Stitch

Side Stitch is played most frequently on hexhex boards (hexagonal boards tesselated with hexagons — examples below), on which the edges have coloured borders (although other shapes are possible — see the game’s image gallery on BGG for examples). The number of colour-sides does not necessarily match the number of sides of the board!

The rules are very simple:

Two players, Black and White, take it in turns to place a single stone of their colour on any empty hexagon on the board. Once placed, stones do not move and are never removed. Players may also pass their turn. The game starts with the pie rule/swap rule.
The game ends when both players pass in succession, or when the board is full.
Once the game is over, the winner is determined by the scores for the players’ groups. Each connected group of same-colour stones gives a score equal to the number of colour-sides that group touches (cells adjacent to two colour-sides count as touching both of them). Each player finds their highest-scoring group, and the player with the highest-scoring group wins. If both players have the same score at that point, then they compare second-highest-scoring group, then third-highest, and so on. Draws are not possible in Side Stitch.

Here are some sample boards I made in Adobe Illustrator based on Craig Duncan’s designs, available for download on BGG:

Side Stitch hexhex-7 board with 9 colour-sides.

Side Stitch hexhex-8 board with 7 colour-sides. This is Craig Duncan’s pick for the ‘standard’ Side Stitch board, as he feels the 169 hexes allow for a suitably complex game without it overstaying its welcome.

Side Stitch hexhex-10 board with 9 colour-sides.

From these sample boards you can see that Side Stitch plays well on wide variety of board shapes and sizes, and with different numbers of colour-sides. The colour-sides also give the boards a lively and appealing visual aspect. Craig Duncan recommends the hexhex-8 board with 7 colours-sides as the ‘standard’ Side Stitch board; I tend to agree with him that this board allows for deep and challenging play without dragging on too long. Having said that the hexhex-10/9-colour board allows for a bit more of strategic battle, and to me is equally as good as the standard board.

The recursive group-scoring mechanism — comparing highest-scoring groups first, then second-highest, and so on until any ties are broken — has appeared in a few recent connection games and related titles, most notably Nick Bentley’s highly successful Catchup (easily my favourite game of his at the moment). This mechanism works particularly well in Side Stitch — draws are impossible and the winner is very easy to determine. In combination with the board’s brightly-coloured sides, it makes a strategically and tactically complex game highly readable in play — following who’s ahead is very straightforward. As a whole, Side Stitch is a fun, elegant and fundamentally flexible game that scales really well.

Side Stitch in play

Despite its simplicity, players discover very quickly that Side Stitch has enormous depth and variety. As players attempt to stitch the colour-sides together to form the highest-scoring group, they’ll need to pay equal attention to interfering with their opponent’s plans as well. The need to connect widely ensures that play spans the entire board surface, and strategic concerns remain paramount even on smaller boards.

Here’s a sample game, one of my early attempts against Ai Ai’s MCTS player on the hexhex-7/9-sided board:

sidestitch9-loss1-end

The AI is playing Black here, and won with a board-spanning group in the centre connected to five colour-sides. As this was an early attempt at the game, I was too wrapped up in my own attempts to connect in the opening phase, and failed to counteract Black’s efforts to split my stones in two. Here’s a GIF so you can see my shame step-by-step:

sidestitch9-loss1-num

After several more losses, I took a game from the AI on the hexhex-8/7-sided board. By this time I’d learned how to balance my attack and defence obligations more appropriately and to manoeuvre a bit more cleverly across the board. The AI (Black) resigned in this position:

sidestitch8-win1-end

You can see that Black made a valiant, and ultimately successful, effort to block me from the left side of the board entirely. However, I was able to extend all the way to the top-right corner, which together with the connections on the right and bottom netted me a group scoring 5 points — an insurmountable margin for Black. Here’s a GIF of the full game:

sidestitch8-win1-num

Now this game is still young, and I’m by no means an expert myself, so it’s difficult to give detailed tactical and strategic advice. But hopefully these sample games can give you some idea of how Side Stitch feels in actual play. For me it’s a standout amongst the many recent connection games — it’s easy to understand but affords some very intricate play. The colourful boards are really appealing, too, and so far the game retains its character and excitement on all the boards I’ve tried.

At a tactical level, connection game basics from Hex et al. will serve you well here; for strategic considerations, you can take some inspiration from games like Star and Starweb. What’s key in Side Stitch, as in other connect-key-cells games, is to impede your opponent’s progress as well as furthering your own connections. You also have to keep in mind the recursive scoring mechanism — if you and your opponent are fighting a close battle, then your second- or third-best group may well decide the game! So don’t forget to develop additional scoring groups, in case the board situation may require a tie-break with your lesser groups.

Side Stitch 6

In response to thread on BGG, Side Stitch designer Craig Duncan designed a way to play Side Stitch using the six sides of the hexhex board, rather than having a different number of colour-sides. In order to keep the play the same and avoid draws the board ends up being a bit different:

side-stitch-6-v1

The rules of Side Stitch 6 are the same as in normal Side Stitch, except that the missing corner cells obviously aren’t playable, and each player starts with stones already in contact with each of the six colours.

Personally I’d rather just play regular Side Stitch and try lots of interesting colour combos, but it’s nice that the game still holds together with six sides or other even numbers of sides, with some small adjustments.

IMPORTANT UPDATE: Side Stitch is now playable at the Gorrion Server! Here’s how the game looks over there — note that scoring is not yet implemented so players have to do that on their own. So far we have the hexhex-8 board with 7 colour-sides available (Craig’s standard board).

side-stitch-gorrion1

UPDATE 2: Side Stitch 10 — hexhex-10 board with 9 colour-sides — is now also available on Gorrion!

gorrion-side-stitch-10

Exo-Hex

The discussion on Side Stitch 6 eventually lead to the development of a sister game, Exo-Hex. Exo-Hex takes the next logical step from Side Stitch 6 and eliminates the colour-sides entirely. Instead, black and white stones are placed outside the boundary of the board — these are called ‘exo-stones’ — and players compete to build groups connected to the largest number of exo-stones. The win condition and scoring mechanism are the same as in Side Stitch. The result looks like this:

exo-hex-7

This new arrangement creates some new wrinkles — the sides are no longer neutral, but are already colonised by pieces of both players. Also, since the sides consist of stones themselves, the sides are connective — in other words, a chain of stones coming in one end of a given side is still connected to a chain of stones coming out the other end.

Speaking personally, I’d still rather play Side Stitch — it has a level of personality and flexibility/extensibility that Exo-Hex doesn’t. But as a consequence of this more focussed design, Exo-Hex is easily playable with any standard hexhex board and two colours of stones, and it’s elegantly simple.

Iris

Our last game of today is Iris, another 2019 invention from Craig Duncan with links to elements of Side Stitch. Iris also has a colourful visual presentation and uses recursive group scoring, but uses a different movement protocol.

An Iris sample game — check the game’s image gallery for more of Craig’s attractive board designs

Iris works like this:

Two players, Black and White, take it in turns to place stones of their colour on the board. Black goes first, and in their first turn may place one stone on any grey interior cell of the board. After that, players may place two stones of their colour on the board subject to these restrictions:
1. If a stone is placed on a coloured cell on the outer rim of the board, the second stone must be placed on the corresponding same-coloured cell on the opposite side of the board.
2. If a stone is placed on an empty grey cell, the second may be placed on any non-adjacent grey cell. If no non-adjacent cells are available, the second stone may not be placed.
The game ends when both players pass, or the board is full. Then players score their groups of same-coloured stones; the score of a group is equal to the number of coloured stones included in that group. The highest-scoring group wins, and the scoring is recursive — if the highest-scoring groups have equal values, then we compare the second-highest, and so on.

I haven’t yet had the pleasure of playing Iris, but the prospect of a connect-the-key-cells game with two moves per turn (this is known as the 122* move protocol) is quite appealing. The additional move would allow for some complex threats to be made and answered during play, and might further encourage the players to attempt adventurous cross-board connections. A nice side-effect of the 122* protocol is that the pie rule isn’t necessary; the first player’s single placement at the start balances out the first-move advantage.

Summing Up

Side Stitch and its kin here show us that the design space surrounding the Star/Starweb connect-the-key-cells concept is rich with possibilities. Side Stitch’s adoption of the colour-sides and recursive group scoring gives it a distinct character from its ancestors, and in play it shines as one of the better connection games I’ve played in recent years. Exo-Hex and Iris are a bit more focussed in design, which has pluses and minuses — of the two, Iris stands out as having some interesting potential. The 122* move protocol with placement restrictions adds an interesting wrinkle to this sub-genre of games.

All told, Craig Duncan’s had a productive couple of years! Out of the three Side Stitch is clearly my favourite design, but if the others become playable via Ai Ai or other venues then that may change. For now I think Side Stitch offers personality, playability and flexibility, and it’s certainly made it to the ranks of games for which I plan to print a mat and encourage others to play.

Next time, we’re going down a somewhat different route. I’ll be covering a single game, the classic Twixt, in significantly more detail than the other games I’ve presented here. This will be possible thanks to David Bush, three-time Mind Sports Olympiad Champion in Twixt, who has not only sent me fantastic content for that post but has given me a Twixt trail-by-fire in some very challenging games. So do look forward to that post — hopefully you’ll come to the end of it packed with Twixt knowledge and ready for the tactical challenges the game has to offer.

Tagged Connection Games, Craig Duncan, Exo-Hex, Games, Iris, Side Stitch

Mar 09 2020

5 Comments

Games

Connection Games IV: Unlur

I promised last time to cover two of my favourite connection games, Unlur and Side Stitch , but you may notice the title of this post only mentions Unlur. I should clarify that my plans haven’t changed as a whole, I’ve just decided to devote an entire post to Unlur instead of covering both games at once. Unlur is a deep and challenging game, so it deserves a bit of explanation — and if I cover Side Stitch separately as well, I can also cover a couple of related games by the same designer (Craig Duncan).

Unlur came about as a result of a game design contest in the Abstract Games magazine back in 2002 — the Unequal Forces Design Competition. The competition challenged designers to create games where the two sides are asymmetric — having different goals and/or different tools with which to achieve the game’s win condition. Designer Jorge Gomez Arrausi won by creating Unlur, a game that took on a very difficult design challenge: how do you create a connection game where the players have unequal goals, yet the game remains balanced?

The Rules

As with most connection games, the rules of Unlur are appealingly simple, but the elegant rules enable remarkable complexity to emerge in play. The first phase of the game, the contract phase, is particularly unique in Unlur, so after introducing the concept here I’ll illustrate how it works in practice with some brief discussion of several real games.

A game of Unlur is played on a hexagonal board tesselated with hexagons — the classic ‘hexhex’ board we’ve seen a few times now. The designer originally recommended playing on a hexhex-6 board, but hexhex-8 is more common — for a deeper and more subtle contest, try hexhex-10 or larger. The game works like this:

Two players, Black and White, compete to form connections between different sides of the board:
- White wins if they connect two opposite sides of the board
- Black wins if they connect three non-adjacent sides (corner cells are considered part of both sides to which they are adjacent)
- If either player achieves the other player’s goal without simultaneously achieving their own, they lose the game immediately
Black’s goal to connect three sides is significantly harder than White’s goal, so a game of Unlur is structured so that the players balance the game themselves before they start playing in earnest. At the start of the game, players are not assigned colours — instead they begin with the contract phase. In this phase, the two players take it in turns to place a single black stone on any empty hex that is not on the outer edge of the board. When one player judges that Black has enough stones in the right positions on the board to give them an equal chance against White, they may pass their turn — from that point they play Black, and the other player is White.
White then makes the next move by placing a White stone on any empty hex, and the players then take it in turns to place a single stone of their colour on the board.

Here’s the final position for a real game of Unlur on a hexhex-8 board played on Richard’s PBEM Server: unlur-8-example

Black won this game by resignation — White gave up because Black’s three stones on the bottom right of the board completely cut off White’s attempt to connect the top and bottom sides, and also ensure an unstoppable connection for Black. Ultimately Black will win by connecting the bottom right corner and top left corner to the bottom left side — remember that corner cells count as part of both sides they’re adjacent to, so Black will achieve their goal of connecting three non-adjacent sides.

The genius of Unlur lies in the contract phase. Essentially the contract is somewhat like an extended form of the pie rule used in many other games, except here players are not assigned colours initially and have complete freedom to decide at what point Black has equal chances. Since neither player has chosen a side at this point, both are invested in making sure that the board is equal at the start, so both will add stones in such a way as to ensure whoever elects to pass and take Black will be competitive but not dominant. The contract phase is of course hugely important to the ultimate outcome of the game, and the completely open nature of it means that opening play in Unlur is both unusual and extremely varied.

The rule enforcing a loss if either player achieves the other’s win condition serves to ensure that draws are impossible in Unlur. In practice this rule affects Black more than White — after all, White’s goal is more economical in terms of stone placement, so it’s less likely they will end up forming Black’s more difficult connective goal before achieving their own.

The contract phase in action

The contract phase is not only ingenious, it’s also complex — how do we decide when Black as equal chances? What sort of moves for Black should we play to ensure equal chances without unbalancing the game?

There are basic rules of thumb we can infer from our experiences with other connection games: the centre of the board is very valuable, so central stones for Black are strong in the contract phase; and conversely, stones closer to the edges of the board are weaker. So as a starting point, we can say that a contract with several central stones for Black would be quite strong, while a contract consisting only of stones close to the edge would require more stones to be placed before we’d consider passing.

The designer adds to this that stones that are widely dispersed are more powerful than stones placed closely together. This often leads to players cautiously adding more stones for Black adjacent to already-placed stones — this still increases Black’s chances but changes the position less drastically than placing stones elsewhere.

Even with these basic ideas in place, judging when to pass in Unlur is difficult, and our decision will have to change depending on the size of the board — on larger boards, Black would need a larger contract to have equal winning chances. Let’s take a look at a few example games on different board sizes, and see how different players have addressed the contract phase in actual play.

First we’ll look at a tournament game played on a hexhex-8 board in 2006 on Richard’s PBEM Server. Black ultimately won this game, and the contract certainly proved important in this case — here’s the game position when the winning player chose to pass and take Black:

unlur-8-diag-contract

In this game the contract consists of just six moves for Black — given that the designer’s analysis on the smaller hexhex-6 board suggested that up to ten stones for Black could still constitute a fair contract, we might conclude that Black’s contract was too weak here. However, remember our rules of thumb — Black’s stones are close to the edge, but also widely dispersed, so they provide a framework for later connections across the board. The stones are also close to several corners, which count as part of either side they’re adjacent to, which again is helpful for Black.

Black’s win in this game made very good use of these contract stones, as we can see:

unlur-8-diag-end

Note that all of the contract stones save the stone on H11 played an important role in subsequent play. The two stones in the bottom left were ultimately blocked by White, but Black nevertheless slipped through the centre to connect the contract stones on the left and upper right with the bottom of the board. So in this case Black’s judgement of the contract proved correct — the number of stones was small, but they formed a framework for connection that Black could exploit well enough to take the win.

Now let’s jump up to a hexhex-9 game and see how the contract phase evolved:

unlur-9-diag-contract

Now this contract seems even more risky than the last one! The winning player took the contract after just three moves — this despite playing on a hexhex-9 board which has 217 hexes, far more than the 169 in the hexhex-8 board of the previous game. Given our rules of thumb we can see that these moves are quite powerful for Black, however; two of them are quite central, and while the stones aren’t widely dispersed they do provide good coverage of the top and top-right of the board.

As it happens, Black was able to construct a nice win here:

unlur-9-diag-end

Note that the two central stones from the contract phase formed a crucial part of the winning player’s connection — in fact the winning Y-shaped configuration spreads out directly from those two stones. Clearly more centrally-placed stones are quite powerful for Black, and can enable Black to form a strong core for a board-spanning connection.

I’d argue though that taking this contract after just 3 moves was still quite a risky play — after all, the board is large and there was still ample room for White to manoeuvre and possibly isolate those stones. We should remember though that the contract is only the first stage of the game, and skilful play can still make up for a less-powerful contract.

In that sense the contract phase in Unlur could also function as an interesting way to balance the game between two players of very different skill levels. I suspect with some detailed analysis we’d be able to develop a reasonably granular system for constructing contracts that help bridge skill gaps between players — perhaps by constructing some pre-set contract placements tailored for different skill levels, or by giving one player additional stones to place in the contract phase. As far as I know this hasn’t really been investigated in detail, but I’d be interested to see some testing of possible handicap play rules.

So far we’ve seen a couple of relatively small contracts — let’s take a look at some more generous ones. First we’ll jump up in size again to this game on a hexhex-10 board, where Black takes a contract four times larger than the last one we studied:

unlur-10-diag-contract

Here Black took the contract after 12 moves. The distribution of stones suggests both players were playing carefully, looking for a balanced and relatively straightforward position — all 12 stones are placed near to the edge of the board, and we see two large clusters of adjacent stones, which as we know are less impactful on the position than more widely-scattered ones. Given the size of the board — 271 hexes, much bigger than the previous game’s 217 — 12 stones in this kind of configuration seems a reasonably fair contract, giving Black a strong framework around the edges but leaving the centre open. We might expect play to focus on that open centre as Black seeks to connect these disparate islands of stones, and White tries to wind their way through the maze to build their own connection.

This ends up being pretty accurate, as we can see in the final position:

unlur-10-diag-end

Black ends up building several strong walls around the centre, blocking White from easily connecting through the middle of the board. White resigned at this point, as it’s clear Black can stop them from connecting to the top, while Black’s structure ensures unstoppable connection between the bottom, right and top sides. In the end Black played cleverly here and utilised the strong points of this contract well — the contract stones helped restrict White’s playable territory along the edges, and Black’s subsequent play largely blocked them out of the centre.

Finally let’s take a look at another well-balanced contract, this time on a rather gargantuan hexhex-11 board (331 hexes):

unlur-11-diag-contract

Here Black took the contract after 15 stones were placed. Note again how many of the stones are clustered together, reducing the overall impact of each placement on the position. However in this case we have a stone placed right in the centre of the board, which is certainly helpful for Black. Given the size of the board and the fact that there’s just one central stone, 15 stones seems like a reasonably fair contract for Black.

The resulting game, another Black win, develops in an interesting way. In issue 12 of Abstract Games, the designer of Unlur explores this kind of opening position and a resulting position called the arrow opening, which we can see in supersized form in this game after the above contract:

unlur-11-diag-end

In this arrow game, White is in quite an unfortunate bind — their long wedge of stones on the bottom-right is completely hemmed in. If we were speaking in Hex terms, we’d say that nearly all of White’s stones are dead — unable to take part in any winning connection. Black has blocked the corner at U11 and constructed a vast wall as well, making a White connection between the lower-left side and the upper-right completely impossible. White’s attempt to snake around the right side to connect to the top is easily stymied by Black using the group of stones on and around D14, so White’s position is utterly hopeless. Black can easily win by connecting to the upper-right side — note this also forms a line, but since Black already connected the bottom (using the corner cell) and the upper-left, Black’s stones would form a 3-way Y connection at the same time, securing the win.

Hopefully these few examples can serve as a useful preview of what a sound contract for Black can look like in Unlur on some of the possible board sizes. The number of possible contracts on any given board size is absolutely enormous — contract length can vary a lot, as we’ve seen, as well as the positions of the stones. In the face of all this variability, a few rules of thumb and experience are the best we can hope for; there are so many ways the contract phase can evolve that set opening sequences are not particularly useful. Besides, your set opening can easily go awry if your opponent decides to go another way — after all, you’re building the contract together, not separately!

After the contract phase, you’ll find yourself using some of the same basic concepts you might use in other connection games like Hex or Y — bridges and so forth. However Unlur is significantly different in one very important aspect: your own stones are never a liability in Hex or Y, but they definitely can be in Unlur! You lose the game if you form the opponent’s connection before your own, so having poorly-placed stones scattered around the board can make this outcome more likely.

During the middle- and end-game of Unlur, it’s also worth keeping in mind some key configurations that ensure a win for one player or the other:

Unlur-config1-edited

In the above pattern, Black completely controls three sides of the board. In this configuration White cannot win — White would need to connect to one of the sides controlled by Black. White will lose either when Black successfully connects or when they are eventually forced to make a foreign connection.

unlur-config2-edited

When White completely controls two opposite sides, Black is completely lost. In order to connect three non-adjacent sides, Black would need to use one of White’s controlled sides, which is impossible. Meanwhile, White still has several different ways to make a winning connection. unlur-config3-edited

This pattern is another one that hands a certain win to White. White can still connect to the top to form a winning line, but Black can’t break through — he can only form a losing line in the attempt.

During the game, watch out for your opponent working toward these configurations — don’t let them get away with it! We can easily forget the ‘foreign connection’ rule and end up in a situation where we’ve unwittingly entered a board position where the foreign connection is the only one available to us.

Resources and where to play

Despite being a relatively well-known connection game and widely respected for its elegance and uniqueness, strategic advice on Unlur is rather hard to come by. Your first stop should be issues 11 and 12 of Abstract Games — the game is introduced in issue 11, and the designer provides some background on his design decisions and some strategic advice in issue 12. Note that he only covers hexhex-6 boards, as he felt that larger boards were too complex:

“…Unlur over a board with eight cells per side becomes very complex and difficult to understand, so now we prefer to play on a board with six cells per side.”

However, since those articles were published many players have come to prefer larger sizes, because there is greater scope for strategic intrigue. I personally prefer larger boards as well, partially because the contract phase takes up a bit less of the overall play time on a larger board, which to me feels a bit better balanced in terms of the playing experience.

From there, you can check the archived version of the designer’s website for further tips, but unfortunately none of the images appear to work anymore. Other than that I can’t really find any detailed strategic discussion anywhere, which is quite a shame.

That being the case, the best way to learn is to try playing some games. Unlur is well-known enough that there are a few options for online play: Gorrion (supports hexhex-8, 10 and 12), Richard’s PBM Server (supports from hexhex-4 all the way up to 13!), igGameCenter (supports hexhex-8 and 10), and Ludoteka (supports hexhex-6 and 8). Unfortunately all these servers are somewhat lacking in Unlur activity, but I’m sure you could rustle up a game or two via BoardGameGeek… or simply contact me if you want to arrange a few!

If you want to play in real life, I’ve made some Unlur boards in a range of sizes — hexhex-6, 7, 8, 10 and 12 — which are directly derived from the original Unlur hexhex-6 board offered in Abstract Games magazine. I posted them on BoardGameGeek with permission from Kerry Handscomb of Abstract Games. There are two versions — one with the original muted bronze board colour and grey background, the other with a white background and lighter board colour. Both are in PDF format and look great printed out on a gaming mat — you can see my own neoprene-printed version below!

: Close-up of my neoprene-printed hexhex-12 Unlur board.

: Yeah… gonna need a bigger table!

Summing up

Unlur is a game of genuine ingenuity, and it offers unique wrinkles you won’t find in any other connection game. The contract phase is a fantastic addition, artfully accomplishing the difficult design goal of a balanced asymmetric connection game. Finally, it’s fun — the contract phase is tense, forcing you to constantly second-guess your opponent and think carefully about each stone and how it will affect the coming game; and the subsequent connection battle feels even more consequential than in other games, given that your own misplaced stones can come back to bite you, potentially forcing you to make your opponent’s connection and lose the game. I give this game my highest recommendation and hope some of you might consider giving it a try.

Related Games

Before I move on I’d be remiss not to mention Cross, Cameron Browne’s connection game inspired by Unlur. Cross is also a connection game played on a hexhex board, but here there is no contract phase — instead, players both are striving to connect three non-adjacent sides of the board, and either player will lose if they make a line connecting two opposite sides of the board. The game plays very differently than Unlur, but the shared element of the Y-connection wins/line connection loses dynamic leads to some tense situations, much like the middle/late-game of Unlur.

Conveniently, you can buy a physical Cross set with a hexhex-7 board from Nestor Games — and the components are generic you can play Unlur on that set too if you want! Nestor also offers hexhex-8 and hexhex-10 boards via the games Iqishiqi and Omega respectively, if you want to play larger games. Cross is also playable on Richard’s PBEM Server.

While I’m here I should also mention Coil — an intriguing game by Nick Bentley that adopts Unlur’s contract phase mechanism. In Coil, players start with a contract phase as in Unlur, except the board starts with black stones in each corner cell, and stones placed during this phase cannot be placed adjacent to one another. Once someone passes and takes the contract as Black, that player must then try to form a loop of Black stones (a loop being defined here the same way as in Havannah), while White tries to prevent the loop from being formed. If Black forms a loop, they win; if the board fills up without a Black loop, White wins. Coil is an interesting take on the asymmetric connection game, and ends up feeling quite different from Unlur. Again it’s playable on any hexhex board with black and white stones, so definitely give it a try after your Unlur games!

Nick Bentley also designed another game with a loop-formation win condition and an Unlur-esque contract phase — Bobina, where players bid not with the black stones but instead with grey neutral stones that can help either player form a winning loop. The concept is very clever but a bit hard to explain briefly here — I’d recommend you go have a read of Nick’s blog post to get a clear picture of it. This is another interesting take on the contract phase, and definitely worth a try if that aspect of Unlur appeals to you. I have to say I slightly prefer Coil due to the simplicity of that game and the asymmetric aspect, but Bobina does offer a unique twist with the neutral stone element.

That’s it for our in-depth look at Unlur — next time I’ll cover Side Stitch and sister games Exo-Hex and Iris.

Tagged Coil, Connection Games, Cross, Games, Unlur

Mar 03 2020

9 Comments

Games

Connection Games III: Havannah and Starweb

In keeping with Part II, today I’m going to introduce two games by one designer — Christian Freeling, who maintains an invaluable website full of his creations including versions playable in your browser. Christian has invented a tonne of well-regarded games over the years, and he has his own opinions on the most essential ones — namely Grand Chess, Dameo, Emergo, Sygo, Symple and Storisende. Although I’m not sure I can agree with most of them, personally speaking — that list is mostly games I certainly admire, design-wise, but don’t particularly enjoy playing.

However, there are two of his games that I find completely, indisputably brilliant: Havannah and Starweb. Both are fantastic additions to the connection game family.

Havannah

Havannah is a connection game that offers a completely unique take on the genre. Connection games are typically characterised by a sense of absolute clarity — the goal is simple, singular, and direct. Connect a thing to other things, and there you go. But in Havannah, players can win in three different ways — and to play well, you need to threaten to do all of them and defend against all of them simultaneously. The consequence is a game of intense depth and richness, and substantial challenge.

Here’s the basics:

Two players, one with black stones and one with white, play Havannah on a hexagonal board tessellated with hexagons (known as a ‘hexhex’ board). The commercial Havannah release used a hexhex board with 8 hexes on a side (169 playable hexes), but Freeling considers a hexhex-10 board to be ideal (271 playable hexes).
The game starts with the swap/pie rule.
Each turn, a player places one stone of their colour on any empty space on the board. Once placed, stones do not move and are never removed.
A player wins when they achieve one of the following configurations (these examples are from real games on Little Golem) —

A ring — a chain of pieces that completely surrounds at least one hex, which can be empty or occupied (by opposing stones or your own):

Rings can get quite elaborate — can you see how White’s convoluted ring formation here?

Rings can also be tiny and enclose just one hex! These are easier to spot so it can hurt when you lose this way….

A fork — a chain of stones connecting three non-corner hexes on three different sides of the board:

Black completes a fork here. Note that it includes a corner hex, at the bottom, but also includes a non-corner one there too, so it still works!

A rather impressively labyrinthine fork here from Black. A clever win from what looks like a hard-fought game.

A bridge — a chain of stones connecting two corner hexagons:

White constructs a fairly convoluted bridge here from the top-right corner to the bottom corner

As you can see already, Havannah puts a lot on your plate as a player. The rules are hardly any more complicated than any other connection game, but the objectives are many and varied. The consequence of this is that at every turn you must be aware of the many possible implications of your opponent’s stones, and you have to learn to catch the signs of key strategic and tactical threats.

In fact the game is so strategically rich that in 2002 Christian Freeling instituted an AI challenge, betting €1000 that no computer could beat him even one game out of 10 on a hexhex-10 board within a decade. Predictably, he lost that challenge in 2012 and lost 3 games of his ten-game match against the machines.

Now one might feel disappointed somehow when computer players surpass humans in games, but honestly having superhuman AI for a newer game is a good thing — it accelerates the decades- or centuries-long process we normally need to really probe how our games hold up at a high level of play. That aside, to be fair to Christian Freeling, his game lasted nearly the full decade; these days, if anyone with some decent computing power is paying attention, any game would be lucky to last a few months. Especially now that AI doesn’t even need to know the rules first to master a game!

Basic Havannah Tips

Havannah, even more than other connection games, really comes alive once you’re armed with a few key strategic and tactical concepts. I’m by no means an expert here — at the end of this section I’ll link you to some people that are — but there’s a few tips I can offer to get you started:

The game plays kind of like a combo of Go and Hex — a certain Go feel is apparent in how important whole-board strategic vision is, and that groups of stones can be ‘alive’ or ‘dead’ depending on their capability to form part of an attacking threat. The Hex side manifests in the moment-to-moment tactics and the importance virtual connections (bridges, in Hex terms) between stones.
Perhaps the most important strategic concept to learn is the frame — a set of stones forming the backbone of an unbreakable winning formation, regardless of the opponent’s response. Check the guides I link below for some examples, and keep an eye out for your opponent threatening to make a frame!
The one-hex ring enclosure — the mill — is a really important tool in Havannah. Rarely will you beat an experienced opponent that way, but building a mill can force a response from your opponent, gaining you initiative — and can interfere with their plans for their own stones, as well. Conversely, it’s important to learn how to defend against mill threats so you don’t fall prey to the same outcomes.
Board size matters! On smaller boards, bridges and forks are powerful. On larger boards (hexhex-10 and up), bridges and forks are harder to build and rings become somewhat more prominent.
Draws are possible in Havannah — but just barely. Out of tens of thousands of online games, there are single-digit numbers of draws that have ever happened! Therefore, don’t think an attempt at a drawing strategy will save you when things go bad — it’s extremely unlikely to work!

An example of a ring frame (Black) and a fork frame (White)

To really dig into the complexities of Havannah, I strongly recommend the brief but comprehensive guide by David Ploog, available in PDF format here (and please see his other amazing guides for other games in the BGG thread here), which covers all the key concepts and includes numerous examples and some problems to test your comprehension.

For a bit of discussion and strategic and tactical guidance for Havannah from the creator himself, do check Christian Freeling’s Havannah website, and his articles in issues 14, 15 and 16 of Abstract Games Magazine (that link takes you to their back-issue archives).

Finally, when you feel up to the challenge, you can play Havannah via Stephen Tavener’s Ai Ai program, the Mindsports website, on Little Golem, Richard’s PBEM Server, igGameCenter, and probably other places too! There’s a physical version of Havannah published by Ravensburger in 1981 that goes for very little on Ebay, but that only has a hexhex-8 board — for larger ones you’ll need to print something up yourself or repurpose another set, like Omega from Nestor Games.

While I’ve been on strike, my wife has helped me to learn Adobe Illustrator so I could make some nice hexhex-10 and hexhex-12 boards usable for Havannah and numerous other games. The final results are available in three colour schemes from the BoardGameGeek Havannah files section. These are sized for printing on 25 inch by 25 inch neoprene playmats, which are a popular way to get sturdy game boards made these days. If you printed them on mats of that size you can use standard 22mm Go stones on these boards.

I also made hexhex boards of size 7, 8, 10, 11, and 12 in the style of the board used on Little Golem, which is probably the most popular place to play Havannah. I like the random splash of colours across the hex grid, so I decided to create a range of print-and-play boards in that style. You can find these boards at my BGG filepage for Havannah along with the other versions.

Hexhex-10 board, with highlighted borders to allow players to use this one board as a hexhex-9, 8, 7, etc. as well. Two other colour schemes are available on BGG, too.

Hexhex-12 board in Little Golem style. I really am proud of this one, as it took some doing to replicate that colour pattern.

Showing off how the game works on my neoprene-printed hexhex-10 Havannah board. My dog Laika is fascinated.

However you go about playing it, Havannah is an absolute gem among the connection games. It’s tactical and strategic, mind-bending, and always enticing to play. If there were any justice in the world it’d be getting played by millions of people like Chess and Go, but alas, we’ve got to dig up players the old-fashioned way. But Havannah’s worth the trouble.

Starweb

One thing you’ll notice about Christian Freeling if you start following developments in the abstract strategy games community is that he has claimed he was retiring from game design about 100 times, yet he always comes back. Starweb appeared during one of these ephemeral retirements — he says the game came to his mind suddenly, basically fully-formed almost out of nowhere. Lucky for us that it did, as in my opinion it’s another masterpiece.

Starweb is a clear descendant of Star/*Star, being a connection game that incentivises connecting certain key points on the board with as few groups of stones as possible. What makes Starweb stand out is both the shape of the board, which creates 18 key corner hexes that drive the gameplay, and the triangular scoring mechanism.

Starweb’s simple and elegant rules lead to board-spanning strategic play, in some ways reminiscent of Havannah. Here’s what the standard board looks like:

Starweb standard board (dubbed size 10 in Ai Ai). It’s a hexhex-7 board with six added chunks of 15 hexes on each side, giving us 217 playable hexes in total, and 18 corner hexes (highlighted in brown). And yes, that is the font from Star Trek — bonus nerd points if you know what language that is underneath the Trek-style logo!

Play is appealingly simple, although the scoring mechanism takes a moment to sink in:

Two players, Black and White, play on the standard Starweb board or one of its smaller variants. The board starts empty.
Play starts with the swap/pie rule.
Each turn, a player places one stone of their colour on any empty hex on the board. Once placed, stones never move and are never removed. Players may also pass their turn and not place a stone.
The game ends when both players pass in succession.
Once the game ends, players calculate their score as follows:
1. Players identify each group of their stones that contains at least one corner cell (a ‘group’ is a connected bunch of like-coloured stones)
2. The score for a group containing n corners is the sum of n and all positive integers less than n. In other words, a group containing 1 corner is worth 1 point; 2 corners = 2 + 1 = 3 points; 3 corners = 3 + 2 + 1 = 6 points; 4 corners = 4 + 3 + 2 + 1 = 10 points; and so on.
3. The player with the highest score wins. In the event of a tied score, the player who placed the second stone wins.

So, to win Starweb, you have to occupy corner cells and connect those corners together into united groups of stones to score more points — the more corners in your group, the more points you score. At the start of the game the players will normally go back and forth occupying corner cells, and from there proceed to wind their way across the board trying to connect them together. This leads to dense, complicated webs of connected stones — hence the name Starweb!

I have to admit I’m not a huge fan of the second-player-wins-draws rule, since there’s already a swap rule in place at the start — that reminds me of Armageddon Chess, where Black wins in the case of a draw, which is pretty widely disliked. But the abstract games community generally seems very adamantly against draws, and designers tend to go to significant lengths to avoid them. That seems somewhat strange to me, since that means the game is by definition unbalanced as one of the players will have a winning strategy with perfect play; I personally slightly prefer Havannah/Shogi scenarios where draws are possible but just quite rare. In any case equal scores in Starweb are going to be pretty uncommon, so it’s not a big issue particularly, but the rule may influence your decision whether or not to swap your opponent’s opening move when going second.

Playing Starweb

The richness of Starweb becomes apparent once you discover that preventing your opponent’s connections between corners can be just as vital as connecting your own. Early on Christian Freeling realised that a minority strategy — in which one player declines to take all the corners they could and instead works to invade the opponent’s territory and deny them connections — is quite viable.

Here’s an example game against AI on a small board that he posted on BoardGameGeek:

starweb-8-corners-small

You can see here that White (the AI) holds more corners (10 vs 8), but Black (Freeling) managed to cut several of them off, denying his opponent the ability to make big-scoring groups. Meanwhile he was able to slice through the centre of the board, leading to a winning score despite holding less corners.

This game also shows off other nice properties of Starweb: the games tend to be intricate and long; and the game plays well even on much smaller boards. The Starweb implementation in Ai Ai allows for boards even smaller than the above, and the game still holds up. It’s definitely more fun on the normal-sized board though.

The minority strategy still works on the large board, too:

After connecting stones 86 and 6 in the bottom right, Black will extend his lead by 5 more points. White is completely lost.

Freeling (Black) again takes less corners here, but manages to sprawl all the way across the board for a big-scoring connection. White has no hope of catching up, as the AI’s largest groups are split down the middle by Black’s connection across the centre of the board, and the extra White corners elsewhere are completely walled off.

Through these sample games we can see that Starweb admits a variety of strategic approaches; when first learning the game we might think grabbing every corner is essential, but as we see above, denying your opponent scoring opportunities can compensate. And by declining corners you can gain the initiative, exchanging turns you’d have spent on building a group for turns you can spend on attacking your opponent’s strategic goals.

At first the game might seem overly mathematical, in that counting corners and calculating scores seems so critical. But in actual play that doesn’t really interfere; once corners are occupied, you don’t need to track them anymore, and that normally happens very early in the game. Subsequently you just need to be aware of how many corners you need to connect to keep your opponent at bay. So the numbers come into play when planning your approach to a particular early-game board situation, but after that you can focus mainly on tactics and trying to connect your groups and execute your plan.

For detailed and enlightening discussion on Starweb’s strategic complexities, you can check out the discussion from Freeling and others on BoardGameGeek. That thread goes into more detail on the sample games I posted, and numerous others as well. There’s also some useful discussion on the Arimaa Forums in this thread, starting at post #104, although sadly the image links are all broken now. Starweb is still a young game, so as more people discover it perhaps we will see start to see guides on strategy and tactics on the level of those we can find for Havannah.

I highly recommend Starweb — you can play on Freeling’s MindSports site, or you can play against AI and human opponents on various board sizes via Stephen Tavener’s AiAi software of course. In my opinion it’s an underrated gem, right up there with Havannah as one of the most strategically satisfying connection games. It’s still early days for Starweb, as it was only developed in 2017, so hopefully as the years go by the game will develop the following it deserves.

Where next?

So, we’ve taken a look at the connection game titan Hex, the quirky and influential family of games by Craig Schensted/Ea Ea; and now two strategic masterpieces by Christian Freeling. Already you could easily spend a lifetime exploring these games and never unlock all their secrets.

Of course that’s far from everything the genre has to offer! Next time I’ll cover one more excellent connect-the-key-hexes game, Side Stitch, and then I’ll spend a fair bit of time talking about Unlur, an ingenious asymmetric connection game where the two players have different winning conditions.

Tagged Christian Freeling, Connection Games, Games, Havannah, Starweb

Science, Philosophy and Miscellaneous Musings

Tag Archives: Games

The Origins of Dai Shogi

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Side Stitch in play

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Havannah