Dr Eric Silverman

One of the many challenges of working on the large Shogi variants is the language barrier.  Not only are the historical documents explaining these games in Japanese, they are in medieval Japanese, and medieval Japanese is written very differently from the modern form of the language.  For a start, many texts were written using only Chinese characters (kanji), and without the helpful hiragana and katakana syllabaries found in the modern language.  On top of that, the usage of kanji has evolved over time, and as with any other language, over the centuries the style of writing has evolved too.

Combine these factors with the generally terse writing style of these old documents, and a natural tendency for Shogi fans to feel quite passionate about their particular interpretations, and we end up with fairly frequent disputes over some rules and piece abilities in these games.  Just to be clear about this, for aspiring Shogi researchers: DO NOT use Google Translate on these old documents!  Google Translate understands modern Japanese (sort of), but has very little idea of what is being said in these old texts.  Even native Japanese speakers have great difficulty interpreting these documents.

Below is an example of the challenges we faced in implementing Dai Dai Shogi, a 17×17 Shogi variant with a large array of 96 pieces of 64 different types for each player.  Somewhat remarkably, most of these pieces have largely agreed-upon powers, but there are two in particular with some disputed abilities: the Furious Fiend, and the Great Elephant.  These are my notes on these pieces that I put together for Stephen, cleaned up and with a bit more explanation.  I share them here as I thought it might be interesting for some of you to see the work that goes on behind the scenes as we try to bring these games to life.

Ultimately we opted to preserve the versions of these pieces that have some historical justification, and allow the player to choose the one they prefer.  As you will see, the pieces change quite a bit depending on which source you use!

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Furious Fiend (promoted Lion)

The Furious Fiend is the promoted form of the Lion in Dai Dai Shogi and Maka Dai Dai Shogi.  Many of you will remember the Lion from Chu Shogi, where this unique and powerful piece dominates the board; for those new to these games, here’s a brief summary of it’s prodigious powers:

• The Lion may move twice in one turn like a King — one step to any adjacent square
• This double-movement power allows numerous unusual abilities:
  • The Lion may step to an adjacent square, then back to its starting square — effectively passing its turn
  • It may capture a piece on an adjacent square, then move back to its starting square, appearing to capture an adjacent piece without moving — this is known as igui, ‘stationary eating’
  • It may capture two pieces in one turn
• The Lion may also jump to any square within the 5×5 area around its starting point (but this then is its entire move for the turn)

In the diagrams you’ll see in this article (and in Ai Ai when using the diagrammatic piece sets), orange squares represent places the piece may step to; the stars represent squares a piece may jump to; an exclamation point indicates a square where capturing without moving is possible (igui); and a red arrow indicates the piece may move unlimited squares in that direction.

Having all of these movement possibilities gives the Lion immense power and flexibility, but in the larger games, the Lion is far from the strongest piece!  One of its beefier cousins is the Lion Dog, which we also need to know about in order to understand the Furious Fiend and the Great Elephant:

• The Lion Dog has a three-step ‘Lion-Power’ move, but restricted to one direction only.  Once the Lion Dog chooses one of the eight possible directions for its move, all of its subsequent moves must take place along that same direction of movement, and the Lion Dog may not move backward past its starting square.
• With its three-step Lion move, the Lion Dog may:
  • Jump directly to the third square (and capture any enemy there)
  • Jump to the second square, then proceed to the third, or backward to the first, potentially capturing two pieces
  • Step outward along that direction up to three times, capturing up to three pieces
  • At any point it can stop, the Lion Dog is not required to use all three Lion-power moves.

So the Lion Dog extends the Lion’s power by allowing potential triple-captures, but its flexibility is reduced somewhat as those captures must all take place along the same line.

In Dai Dai Shogi and Maka Dai Dai Shogi, there are compound pieces that combine Lion and Lion-Dog moves with the moves of other pieces.  One of those is the Furious Fiend, the promoted form of the Lion itself.

There are two main versions of this piece:

1. Lion + an option to slide three steps in any of the eight directions
2. Lion + Lion Dog

The evolving consensus at this point is that (2) is the correct move.  (1) is likely a relic of a misunderstanding that pervaded the English literature on these games for a long time, where the Lion Dog was thought to have a three-step move in any direction without Lion power, but that’s considered a misapprehension now.  For those of you who may have physical Dai Dai Shogi sets from The Shogi Association, the manuals included in those games include this version of the Lion Dog; for that reason, this version is sometimes referred to as being part of the ‘TSA rules’.

So, when that non-Lion-powered move was prevalent, and the old texts said Furious Fiend moved as ‘Lion + Lion Dog’, when you combine these moves you end up with (1).  But with our corrected understanding of the Lion Dog, we get (2).  In our Ai Ai implementation, we have allowed players to choose which version of the Furious Fiend to use in Dai Dai Shogi and Maka Dai Dai Shogi, since both have been used in modern play.

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Great Elephant

Some Shogi scholars suspect that Maka Dai Dai Shogi had some fans back in the day — it’s the most consistently-described of the very large games in the historic sources, with few discrepancies despite the texts being written years apart by different people.  Players also developed a chant in Chinese that they’d use to remember the initial setup, so that’s an indication it was being played some amount.  This can be helpful when questions arise about other games, because if that same piece appears in Maka Dai Dai we may be able to get a more consistent picture of how that piece should work.

The Great Elephant, however, does not appear in Maka Dai Dai Shogi and instead only shows up in Dai Dai Shogi (and the 25×25 Tai Shogi), where it is the promoted form of the Lion Dog; in Maka Dai Dai Shogi, the Lion Dog is one of the strong pieces that demotes to Gold General.  The Great Elephant is described in very different ways in the available historical sources that explain the rules of Dai Dai Shogi.  These are the main options, according to the sources I’ve seen before:

1. The piece doesn’t exist at all (!) [two sources don’t have the Lion Dog promote to anything, so this piece doesn’t exist in Dai Dai Shogi in those documents]
2. The piece moves as claimed in a note on Japanese Wikipedia: Steps 1-2 squares diagonally forward, or unlimited slide in all other directions *and* it may jump over up to 3 pieces, friend or foe, and continue its slide on the other side
3. The piece moves as described in (2), except that it *cannot* jump over pieces
4. The piece moves as in Taikyoku Shogi: steps 1-3 squares diagonally forward, or unlimited slide in all other directions and it may jump over up to 3 pieces and continue sliding on the other side of them.
5. The piece may step 1-5 squares sideways or diagonally backward, or 1-3 squares in the other directions [this move is widely discredited now, given that it’s based on the old TSA interpretation of the Lion Dog].

However, in an effort to further develop our understanding of this disputed piece, I obtained a copy of the ancient document Shogi Rokushu no Zushiki from the Japanese National Diet Library, and have gone through every scrap of info on Dai Dai Shogi in there.  This is document includes the Great Elephant as the promotion for the Lion Dog.  After deciphering the notation based on the text descriptions of various pieces’ movements, and examining the diagram of the Great Elephant’s move:

I believe this diagram from the text indicates the following move:

• Lion-Dog-style 3-step Lion Power in the four orthogonal directions and diagonally backward
• Or it may slide unlimited squares in the four orthogonal directions or diagonally backward
• Or it may step 1-2 squares diagonally forward.

The key is the three slashes over the longer lines.  The text very clearly states that the long lines indicate unlimited sliding moves in those directions.  There is only one other piece that is given a text description that has the three slashes overlapping the longer lines, and that is the Teaching King in Maka Dai Dai Shogi’s section in the text, and that text says the Teaching King functions as Lion Dog + Free King.  So, we can infer from this that those three slashes indicate Lion Dog moves in those directions:

Here we have the source of some confusion.  The Lion Dog’s move is described in this text using the word ‘odoru’, which means ‘dance’, and depending who you ask, ‘odoru’ in this context either means a Lion-Power move, or a leaping move where you can jump over some number of other pieces.

So that leaves us with two plausible options, depending on how we interpret ‘odoru’:

1. if ‘odoru’ means ‘leap over stuff’: that’s the Japanese Wikipedia move, (2) above
2. if ‘odoru’ means ‘Lion Power move’: that’s my interpretation above

However, I consider (2) to be the more plausible interpretation, and easier to place among the rest of the Dai Dai Shogi army.  That move would make the Great Elephant a promotion above the Lion Dog, given the added mobility, but reducing the Lion-Power directions to six makes it less powerful than the Teaching King/Buddhist Spirit.  This makes some intuitive sense, as the Teaching King and Buddhist Spirit are the strongest Lion-Power pieces in Maka Dai Dai Shogi, and typically the larger games introduce additional, more powerful pieces over their smaller cousins.  Meanwhile, (1) would require a new mechanic that only appears for this single piece, and does not otherwise appear in Dai Dai Shogi at all, so it does not seem likely.  However, Dai Dai Shogi does introduce two hook-moving pieces that can perform double Bishop or Rook moves, so it’s perhaps not impossible that the creators would introduce another form of movement as well.

I should mention that Shogi Rokushu no Zushiki is known for having a lot of differences in how pieces move in all the games it covers, and that includes Dai Dai Shogi.  However, the power-pieces in each game do seem to agree with other sources from that period.  The beginning of the text opens with the author complaining about transcription errors and incorrect piece names in other documents about Shogi, so he is presenting himself as correcting the historical record, but today we consider many of his claims to be questionable.  In any case, I feel it’s worthwhile to try to understand the Great Elephant move presented in this text and see whether it fits in the game as we know it today, and give players a chance to try it for themselves*.

The English/Japanese Wikipedia seems to have simply removed the Lion Dog moves from the Shogi Rokushu no Zushiki move and given the Great Elephant the six ranging moves and diagonally-forward stepping moves only.  This is nice and simple but I don’t think this is a correct interpretation of this particular text.  However, this move has been widely used until now, and certainly is a playable variation with some historical justification.

The Final Move Choices

We are left with three main usable interpretations of the Great Elephant in Dai Dai Shogi/Tai Shogi, after we discount the one related to the old TSA Lion Dog move, plus one variant for use in Taikyoku Shogi only:

1. 1. Steps 1-2 squares diagonally forward, or slides unlimited squares in the four orthogonal directions + diagonally backward, or 3-step Lion Power move in those same six directions [my translation of SRZ]
   2. Steps 1-2 squares diagonally forward, or slides unlimited squares in the four orthogonal directions + diagonally backward [English/JP Wikipedia]
   3. Steps 1-2 squares diagonally forward, or unlimited slide in all other directions *and* it may jump over up to 3 pieces, friend or foe, and continue its slide on the other side [JP Wikipedia move in the notes]
   4. In Taikyoku Shogi it moves as (2), except it may move 1-3 squares diagonally forward instead of 1-2.  Hopping-ranging moves are commonplace in Taikyoku Shogi, so that move is uncontroversial in that game.

Given the lack of consensus, we opted to implement all three possible moves for Dai Dai Shogi and Tai Shogi (1, 2 and 3 above), and allow the player to choose.  So at the start of the game, you may choose your preferred move of the Furious Fiend and the Great Elephant before starting play.  The Taikyoku Shogi move will be relevant once we get to that game!

We also include an alternative implementation of Dai Dai Shogi which does not include the Great Elephant, since two historical sources indicate that the Lion Dog does not promote at all.

As for the diagrams, for the range-jumping move in (2) and (4), we use a numbered circle to indicate how many pieces may be jumped over in one move.  In Taikyoku Shogi this number varies between pieces, so we will continue to use this notation when we start working on that game and more range-jumping pieces appear.

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Conclusions

So, after all that work, we ended up with a robust implementation of Dai Dai Shogi which we think covers all the main bases for the Great Elephant: the long-distance sliding piece espoused by English Wikipedia; the long-distance jumper suggested in the notes on Japanese Wikipedia; and the powerful Lion Dog compound suggested by the text of Shogi Rokushu no Zushiki.  Players may also choose between either version of the Furious Fiend.  Finally, we also allow players to ditch the Great Elephant entirely.

Having experimented with these variations myself, here are my impressions (note that I’m excluding the Taikyoku Shogi version, which will feel very different in that game, given the enormous 36×36 board and the presence of other range-jumping pieces):

This piece is highly mobile, which makes it very useful in the endgame, where mobility becomes very powerful as the board starts to empty of other pieces.  However, the lack of Lion Power does mean that players have to consider their strategic aims when deciding whether to promote this piece.  In a congested middlegame position, for example, one may want to avoid promoting the Lion Dog early so that the Lion Dog still presents a powerful capturing threat.  In a late-game situation where enemy defences have thinned out, then making a capture and promoting the Lion Dog may be well worth it, as the new-found mobility will come in handy.

This piece is amazingly fun to use!  Given the congested, high-density setup of Dai Dai Shogi, having the ability to leap any distance over three pieces is hugely helpful.  Promoting this piece loses the Lion Dog’s multi-capture abilities, certainly, but in exchange you gain incredible flexibility, plus the option of threatening the enemy King even over a dense wall of protective pieces.  I’d imagine that few players would hesitate to promote their Lion Dogs if this promotion is available; the piece just gives you so many new options when on the attack, and as the only long-range jumper on the board, it’s very hard for your opponent to chase it down.

I have had so much fun with this beast that I’m getting very excited to work on Taikyoku Shogi further down the line, where lots of these range-jumping pieces will appear.

This piece ends up feeling surprisingly well-balanced, in my opinion, with the rest of the power-pieces available in Dai Dai Shogi.  When promoting to this from Lion Dog, one loses the option to perform multiple captures in all eight directions, but in return gains significant mobility.  However, that mobility is less useful on the attack, as the forward diagonal moves are only two-square steps.

The result is a piece that feels like an upgrade from the Lion Dog, but nevertheless requires finesse to use effectively.  The Great Elephant also proves to be a powerful and mobile defender, able to move backward into a defending posture quickly and mop up several opposing attackers at once.  To me it’s an interesting piece to use, and it feels like a viable addition to the game.

In my testing, the presence of the more powerful Elephants, either the SRZ version above or the range-jumping variant from Japanese Wikipedia, has not significantly influenced the length of the typical game.  Dai Dai Shogi is a big game with lots of pieces on the board, and even the most powerful pieces have to bide their time until their powers can flourish; otherwise they have to run away from constant threats of capture from the hordes of weaker pieces**.  So the stronger Elephants have a big influence in the endgame, but overall don’t feel overly unbalancing.  In my opinion, though, the SRZ version is the one I would advocate if you want a stronger piece than the English Wikipedia version; the range-jumping Elephant feels a bit out of place with its highly unusual movement abilities, whereas the SRZ variant feels more at home amongst the other Lion-Power pieces on the board.

As for our furious friend the Furious Fiend, both versions are a straight upgrade from the Lion, and I don’t think either one makes a significant difference in the overall shape of the game.  The Lion + Lion Dog version can make additional captures in some circumstances, but against a good opponent this is unlikely to come into play very often — a good player will never allow three of their strongest pieces to be in range of a Furious Fiend at the same time!

In this case the choice comes down more to personal preference.  I like the more powerful Lion + Lion Dog variant, as it feels like a more significant upgrade over the Lion, which adds incentive to move the Lion into battle in the first place.  I also feel it’s more likely to be the intended move, given that the old documents position it as Lion + Lion Dog and we now understand the Lion Dog move to have multi-capture abilities.

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Next Moves

So, at this point we are close to finishing our time with Dai Dai and Maka Dai Dai Shogi, so you can look forward to a more detailed look at those games on this blog in the near future.  In the meantime we are getting started on Tenjiku Shogi, which is an exotic and exciting game with a lot of disputed rules and pieces to sort through, so I may do another ‘translator’s notes’ article on that game once we complete it.

I hope some of you out there may give these games a try in Ai Ai when you have a chance; they really are unique games in the history of the Chess family, and deserve your attention!  Though these games are many centuries old, they have unique ideas and pieces that still stand out today, even amongst the thousands of Chess variants that have been constructed since.  Give them a try, and you may find you enjoy the sheer immensity and creativity of these fascinating games.

UPDATE: I’ve been really pleased to discover that the Dai Dai Shogi page on Wikipedia has been updated with a diagram of the move I suggested from my interpretation of Shogi Rokushu no Zushiki:

I’d like to give a hearty thank you to HG Muller and Wikipedia user Double Sharp for taking note of my arguments here and presenting this move as one possible interpretation on the Wiki page, I very much appreciate that my work on this was recognised.  I also agree with both of them that this piece is seriously confusing, and we’ll probably never be able to definitively decide whether it should even be in the game at all!

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* I suspect some readers may be wondering: why did I pick out this one piece and elevate it to the status of a plausible move, when the rest of the source text is viewed with skepticism (and justifiably so)?  My answer is that the Great Elephant in particular is a mysterious piece, sometimes existing and sometimes not, and when it does exist, every source seems to have different opinions about its moves.  While Shogi Rokushu no Zushiki has a lot of move descriptions that don’t match other sources, it *is* a source that actually contains the Great Elephant, and so I decided to investigate it.  I found that the move looked more complex than I’d expected, and yet the positioning of the stepping and sliding moves exactly matched the diagram provided on Wikipedia.  That led me to think that it would be worth looking more deeply at this move, and what I found seemed potentially interesting to try within the current agreed-upon Dai Dai Shogi ruleset, even when taken out of the context of the SRZ account of Dai Dai Shogi.

I left the other moves from SRZ aside, as the other pieces in Dai Dai Shogi have a consensus regarding their moves and abilities, so in that context I don’t see a need to replace them with moves from a single divergent source.  That’s not to say some of them aren’t interesting; SRZ gives the Golden Bird almost the reverse of the Great Elephant move, with Lion Dog moves on the front diagonals and limited 3-step retreating moves (without Lion Power).  But that piece exists in Maka Dai Dai Shogi and the moves appear to be consistent across the other sources, so I can’t see a justification for replacing it with the SRZ move.

In short, I wanted to know more about the Great Elephant, and found the move in SRZ to be both plausible and interesting, so I wanted to give players a chance to try it!

**This phenomenon of stronger pieces sometimes being a liability is seen in all Chess-like games and was dubbed the levelling effect by great Chess variant explorer Ralph Betza.  Put simply, because different pieces have very different levels of power and influence on the board, a threat against our weaker piece from the opponent’s stronger piece is often no threat at all, because if those pieces are traded off we still end up ahead in material strength on the board.  However, a threat against a stronger piece from a weaker piece must be defused immediately, because if we allow that trade of material we hand the opponent a strength advantage.  This is why the advice in the Chess opening is never to bring the Queen out too early:  your opponent can attack it and chase it away with their weaker pieces, as you’re forced to retreat it to avoid a bad exchange, leaving you under pressure and lacking initiative.

The levelling effect is also evident in large Shogi variants, where the board tends to be thick with dozens of pieces, many of them weak.  The powerful pieces therefore have to be deployed cautiously, given the sheer number of possible threats from the opponent’s huge army.

Some large Shogi pieces are not quite so vulnerable to this however, simply because they are ridiculously powerful.  Tenjiku Shogi’s Fire Demon is a good example — the Fire Demon instantly destroys all adjacent enemy pieces, even on the opponent’s turn, so threats against it have to be made at a distance.  Similarly, the various Lion-Power pieces cannot be chased away by single-step-moving pieces, because those pieces have to be adjacent to threaten to capture, and the Lion-Power piece can simply take them at will with an igui capture.

Note that the SRZ Great Elephant does have vulnerable areas along the front diagonals, where it cannot make a Lion Dog move!  This reduces its attacking presence, as there are several weak pieces with short movement ranges (2-3 squares) that could make credible threats along those diagonals, forcing the Great Elephant to retreat or be captured.