Dai shogi


Dai shōgi or Kamakura dai shōgi is a board game native to Japan that is a local variant of chess. It developed from Heian era shogi, and is similar to standard shogi in its rules and game play. Dai shogi is only one of several large board shogi variants. Its name means large shogi, from a time when there were three sizes of shogi games. Early versions of dai shogi can be traced back to the Kamakura period, from about AD 1230. It was the historical basis for the later, much more popular variant chu shogi.

Rules of the game

Other than the additional pieces, the rules of dai shogi are thought to have corresponded very closely to those of its descendant chu shogi.

Objective

The objective of the game is to capture the opponent's king and, if present, the prince, which counts as a second king; or to capture all the other pieces, leaving a bare king or bare prince. Unlike standard shogi, pieces may not be dropped back into play after capture.

Game play

Two players alternate, making a move with Black moving first. A move consists of moving a piece either to an empty square on the board or to a square occupied by an opposing piece, thus capturing that piece; and optionally of promoting the moving piece, if the move enters the promotion zone, or if it is a capture and any part of it is in the promotion zone.

Game equipment

Two players, Black and White, play on a board ruled into a grid of 15 ranks and 15 files with a total of 225 squares. The squares are undifferentiated by marking or color, unlike a Western chess board.
Each player has a set of 65 pieces of 29 different types. In all, a player must remember 36 different moves. Each piece has its name written on it in Japanese kanji. The writing is typically in black. On the reverse side of most pieces there are characters to indicate the piece's promoted rank, typically written in red. The pieces are wedge-shaped and their orientation indicates which player they belong to, as they point toward the opposing side. The pieces are of slightly different sizes, from largest to smallest they are:
Listed below are the pieces of the game and, if they promote, the pieces they promote to. Names are rough translations that have become somewhat standardized in English. Pieces are listed alphabetically by their English name.
The promotions apply only to pieces which start out with the ranks in the left-most column, that is, pieces with these ranks written in black; promoted pieces with those same ranks written in red may not promote further. Pieces which only appear upon promotion, that is, names which only occur written in red, are marked with an asterisk. The king, queen, and lion do not promote.
Piece nameKanjiRomajiAbbrev.PromotionBetza notation
angry boar嗔猪shinchō嗔gold generalW
bishop角行kakugyō角dragon horseB
blind tiger盲虎mōko虎flying stagFrlbW
cat sword猫刄myōjin猫gold generalF
copper general銅将dōshō銅side moverfKbW
dragon horse龍馬ryūma1馬horned falconBW
dragon king龍王ryūō龍soaring eagleRF
drunk elephant酔象suizō象princeFfrlW
evil wolf悪狼akurō狼gold generalfrlK
ferocious leopard猛豹mōhyō豹bishopFfbW
flying dragon飛龍hiryū—gold generalB2
*flying ox飛牛higyū牛'BfbR
*flying stag飛鹿hiroku鹿'fbRK
*free boar奔猪honcho猪'BrlR
go-between仲人chūnin仲drunk elephantfbW
gold general金将kinshō金rookWfF
*horned falcon角鷹kakuō鷹'BrlbRffD
iron general鉄将tesshō鉄gold generalfK
king 玉将gyokushō玉—K
king 王将ōshō王—K
kirin麒麟kirin麒lionFD
knight桂馬keima桂gold generalffN
lance香車kyōsha香white horsefR
lion獅子shishi獅—NAD
pawn歩兵fuhyō歩gold generalfW
phoenix鳳凰hōō鳳queenWA
*prince太子taishi太'K
queen奔王honnō1奔—Q
reverse chariot反車hensha1反whalefbR
rook飛車hisha飛dragon kingR
side mover横行ōgyō横free boarWrlR
silver general銀将ginshō銀vertical moverFfW
stone general石将sekishō石gold generalfF
*soaring eagle飛鷲hijū鷲'RbBffA
vertical mover竪行shugyō竪flying oxWfbR
violent ox猛牛mōgyū猛gold generalR2
*whale鯨鯢keigei鯨'fRbQ
*white horse白駒hakku1駒'fQbR

Setup

Below is a diagram showing the initial setup of the board.

Movement and capture

An opposing piece is captured by displacement: That is, if a piece moves to a square occupied by an opposing piece, the opposing piece is displaced and removed from the board. A piece cannot move to a square occupied by a friendly piece, that is, by another piece controlled by the moving player.
Each piece on the game moves in a characteristic pattern. Pieces move either orthogonally, or diagonally. The lion and knight are exceptions in that they do not move, or are not required to move, in a straight line.
Many pieces are capable of several kinds of movement, with the type of movement most often depending on the direction in which they move. The movement categories are:

Step movers

Some pieces move only one square at a time. If a friendly piece occupies an adjacent square, the moving piece may not move in that direction; if an opposing piece is there, it may be displaced and captured.
The step movers are the king, drunk elephant, blind tiger, ferocious leopard, generals, angry boar, cat sword, evil wolf, go between and the 15 pawns on each side.

Limited ranging pieces

The violent ox and flying dragon can move along a limited number of free squares along a straight line in certain directions. Other than the limited distance, they move like ranging pieces. See below.

Jumping pieces

Several pieces can jump, that is, they can pass over any intervening piece, whether friend or foe, with no effect on either. These are the lion, kirin, phoenix and knight.

Ranging pieces

Many pieces can move any number of empty squares along a straight orthogonal or diagonal line, limited only by the edge of the board. If an opposing piece intervenes, it may be captured by moving to that square and removing it from the board. A ranging piece must stop where it captures, and cannot bypass a piece that is in its way. If a friendly piece intervenes, the moving piece is limited to a distance that stops short of the intervening piece; if the friendly piece is adjacent, it cannot move in that direction at all.
The ranging pieces are the queen, dragon king, dragon horse, rook, bishop, vertical mover, side mover, reverse chariot and lance. Only the queen can range along all eight directions.

Lion moves (multiple captures)

The lion has sequential multiple-capture ability, called a 'lion move', as do the soaring eagle and horned falcon to a lesser extent. The details of these powerful moves are described for the lion below.

Promotion

The promotion zone is the 'enemy camp', the farthest five ranks of the board, which are mostly occupied by the opposing player's pieces when the board is first set up. When a promotable piece makes a move entering the promotion zone, or makes a capture within the promotion zone—including moves entering, leaving, or moving entirely within the zone—it has the option of "promoting" to a more powerful rank. Promotion is effected by turning the piece over after it moves, revealing the name of its promoted rank. Promotion is not mandatory, and in some cases it may be beneficial to leave the piece unpromoted. Promotion is permanent and promoted pieces may not revert to their original rank. If a piece is not promoted upon entering the promotion zone, then it may not promote until it leaves the zone and reenters unless it makes a capture.
Promoting a piece has the effect of changing how that piece moves. See below.
If a piece that cannot retreat or move aside advances across the board until it reaches the other side, it is trapped. This applies to the pawn, stone general, iron general, knight, and lance. This would hardly occur in practice, because all of these but the knight promote to pieces that keep their old moves, and stalemate is a loss for the stalemated player. The situation of the knight is unclear, as it promotes to a piece that does not keep its old moves, and thus there could be a reason to defer its promotion. In chu shogi, which is descended from dai shogi, this situation applies to the pawn, which therefore gets a second chance to promote at the last rank on a non-capture: this second chance can likewise be declined, leaving the pawn as an immobile "dead piece". Whether this rule applies to the knight in dai shogi is uncertain, both because this rule might be a later refinement to chu shogi, and because the Edo-era sources have numerous lacunae when describing the rules of the variants other than sho shogi and chu shogi.
The promotion rules of dai shogi may have changed significantly over time. The promotion rules in the earlier Heian shogi and Heian dai shogi provide for all weak stepping pieces to promote to the gold general, which is true for sho shogi and modern shogi. However, in chu shogi many of these pieces have changed promotions to ranging pieces in the initial setup. Dai shogi has a mixture of these rules: the weak steppers or limited rangers unique to dai shogi all promote to the gold general, but those present in chu shogi keep their promotion from the latter game. It is likely that these differing promotions in chu shogi are a later historical innovation, that was later copied back into dai shogi when chu shogi became more popular than dai shogi.

Individual pieces

Following are diagrams that indicate the movement of each piece. Pieces are listed roughly in order, from front to back rows, with pieces making similar moves paired. Pieces with a grey heading start out in the game; those with a blue heading only appear on the board as a promoted piece. Betza's funny notation has been included in brackets for easier reference, with the extension that the notation xxxayyyK stands for an xxxK move possibly followed by an yyyK move, not necessarily in the same direction. Larger numbers of 'legs' can be indicated by repeated application of 'a'. By default continuation legs can go into all directions, but can be restricted to a single line by a modifier 'v'. The default modality of all legs is the ability to move and capture: other possibilities are specified explicitly. Square brackets are used to make it clear what operators the a modifier chains together: thus DaK would denote a dabbaba move followed by a king move, but D would denote a piece that can move as a dabbaba, or twice as a king.

Repetition

A player may not make a move if the resulting position is one that has previously occurred in the game with the same player to move. This is called repetition. Note that certain pieces have the ability to pass in certain situations. Such a pass move leaves the position unchanged, but it does not violate the repetition rule, as it will now be the turn of the other player to move. Of course, two consecutive passes are not possible, as the first player will see the same position as before.

Check and mate

When a player makes a move such that the opponent's only remaining royal could be captured on the following move, the move is said to give check; the king or prince is said to be in check. If a player's king or prince is in check and no legal move by that player will get it out of check, the checking move is also mate, and effectively wins the game.
Unlike Western chess, a player need not move out of check in dai shogi, and indeed may even move into check. Although obviously not often a good idea, a player with more than one royal may occasionally sacrifice one of these pieces as part of a gambit.

Game end

A player who captures the opponent's sole remaining king or prince wins the game. In practice this rarely happens, as a player will resign when checkmated, as otherwise when loss is inevitable.
A player who makes an illegal move loses immediately.

Game notation

The method used in English-language texts to express shogi moves was established by George Hodges in 1976. It is derived from the algebraic notation used for chess, but modifications have been made for dai shogi.
A typical example is P-8f. The first letter represents the piece moved. Promoted pieces have a + added in front of the letter. e.g., +P for a gold general. The designation of the piece is followed by a symbol indicating the type of move: - for an ordinary move or x for a capture.
Next is the designation for the square on which the piece lands. This consists of a number representing the file and a lowercase letter representing the rank, with 1a being the top right corner and 15o being the bottom left corner.
If a move entitles the player to promote the piece, then a + is added to the end to signify that the promotion was taken, or an = to indicate that it was declined. For example, Nx7d= indicates a knight capturing on 7d without promoting.
In cases where the above notation would be ambiguous, the designation of the start square is added after the designation for the piece in order to make clear which piece is meant.
When a 'Lion', 'Horned Falcon' or 'Soaring Eagle' captures by 'igui', the square of the piece being captured is used instead of the destination square, and this is preceded by the symbol '!'. For example, a Lion on 8c capturing a piece on 9d would be shown as Lnx!9d.
When a piece makes a double capture with 'Lion' powers, both captures are shown in the order that they were made. For example, a Lion on 3g, capturing a piece on 3h and then capturing another on 2i, would be represented by Lnx3hx2i.
Moves are commonly numbered as in chess.