Dai Dai Shogi

Dai Dai Shogi is one of the 'Large Shogi variants' of which records have been preserved since medieval times, and large it is indeed. On a 17x17 board each side starts with 96 pieces of 64 different types, making this double the size of Chu Shogi, which was the dominant form of Chess in Japan in those days. The vast majority of piece types have only stepping or (limited-range) sliding moves, as oblique leapers are virtually non-existent in Shogi, give or take an occasional Knight. The number of piece types can be so large because the pieces in general lack the 8-fold symmetry that all orthodox Chess pieces (except Pawn) have. By giving the pieces different ranges in the various directions this extraorinarily large number of piece types can be constructed. Some pieces even break the left-right symmetry, which the FIDE Pawn still respects.

So most of the 64 piece types have quite ordinary Rook or Bishop moves, and many are in fact 'steppers', which have a sub-set of the moves of an orthodox King. A large number of these pieces is in fact exceedingly weak, with steps in just 2 or 3 directions.

What spices up the game is a hand full of very powerful pieces, unique to the middle and large Shogi variants. One of their ingredients is the so-called 'Lion power', the ability to continue moving after having made a capture, and thus able to make multiple captures in one turn. Some other pieces are 'hook movers', sliders able to turn one corner in a place of their choosing, wich thus have an enormous number of move targets.

Setup

Dai Dai Shogi is characterized by a highly asymmetric setup, where most pieces that promote are present only in a single copy, while the piece they promote to is also present in the initial setup, and then doesn't promote. This can be interpreted as that you start with one unpromoted and one already promoted copy of each promotable piece. Most stepper pieces are not promotable, and you typically start with a pair of those. The weaker pieces are positioned directly behind the Pawn rank, while the promotable stronger pieces occupy the back rank. Only 4 promoted types are not present in the initial setup.

Pieces

Lion

A Lion moves as King, but up to twice per turn, in independent directions, also if the first King move captures something. The ability to move on after a capture is called 'Lion power'. The combination of two steps can also be taken as a hop, i.e. over an occupied square without disturbing it, when it does not return to the starting square. So the Lion can:

• move or capture by leaping to any square in the 5x5 area surrounding it,
• capture an adjacent piece, and then go on moving or capturing once more as a King,
• move to an adjacent empty square and back, effectively passing a turn.

Furious Fiend, Lion Dog

A Furious Fiend moves as a Lion or Lion Dog. A Lion Dog can make up to three steps along any ray passing through it. It can return to, but not overshoot its starting square. Each of the steps can be a move, a capture or a hop, with the exception that it cannot hop back to its startng square. So it can:

• move and capture as King, optionally taking out an enemy on the second square (2 steps out, one in),
• move or capture to the second square on any ray, optionally taking out an enemy on the square it passes over in the process,
• move or capture to the third square on any ray, optionally taking out any enemies on the squares it passes over in the process,
• capture a piece adjacent to it without moving,
• pass a turn when an adjacent square is empty.

Hook Mover, Long-Nosed Goblin

The Hook Mover is a Rook that can (but does not have to) make one 90-degree turn in its path. The Long-Nosed Goblin is a Bishop that can do that (and in addition has an orthogonal step to break color binding). Like any slider, they have to stop at the point where they capture, and the (bent) path they move along must be empty up to that point.

Kirin, Phoenix, Poisonous Snake

These pieces can leap directly (in addition to steps in other directions) to the second square along some orthogonal or diagonal. Such a jump is relatively rare in Shogi, when not part of a move with Lion Power.

Pawn

The Pawn occurs in its Shogi form, i.e. it captures as well as moves straight ahead.

Rules

Goal

The game is won by capturing the opponent's King.

Promotion

Many pieces in the initial setup can promote (but, surprisingly, not Pawns). This can happen anywhere on the board, whenever they capture something. There is no choice in what you promote to; each piece has a fixed promoted form. Promotion (for promotable pieces) is mandatory at the end of every move that captured something.

Promotion is irreversible: once promoted the piece stays promoted for the rest of its life in the game.

Repetition

The historic sources mention that repetition is forbidden, but do not elaborate on which side carries the burden to avoid it. It is likely that you could not win by perpetually checking your opponent, and that the burden to deviate was thus upon the checker, like in all Asian variants. The modern interpretation of this rule is that evading a perpetual chase, with moves that do not attack anythinging should also be always allowed, so that the chaser must deviate, and that repeats reached without either side attacking anything should be draws.

Notes

The Lion and Lion Dog obtained through promotion of the Barbarians are not really the same as those initially present, as the latter can still promote (to Furious Fiend and Great Elephant), while the former cannot promote anymore.

The promoting pieces are all on the 2nd, 3rd and 4th rank, and the central three and the edge pieces usually do not promote. With only few exceptions pieces stand very close to the one they promote to.

Rule variations

This description follows the rules described in the English Wikipedia. These are not uncontested, though: the Japanese Wikipedia gives different moves for Old Kite and Poisonous Snake. The Lion Dog move has also been much debated, especially since the given move makes it the only piece in Dai Dai Shogi that 'promotes' to a weaker one. (This argument might not carry much weight, though, as only the oldest source has the Lion Dog 'promote' this way; in two other historic descriptions the Lion Dog is a non-promoting piece.) Several alternative moves have been proposed, differing in the amount of lion power this piece has. This also reflects on the move of the Furious Fiend, which in historic sources is said to move as "Lion or Lion Dog". Apparently the historic sources are ambiguous enough to allow for such deviating interpretations. The game of course might have known local variations even in historic times, or the write-up of their rules might have been distorted by copying errors.

A 50% smaller version of Dai Dai Shogi, featuring a representative selection of the pieces on a 13x13 board, but otherwise using identical rules, was designed to make this game more accessible. It was published under the name Cashew Shogi.

Last revised by A. M. DeWitt.