Other than the additional pieces (the iron and stone generals, knights, angry boars, cat swords, evil wolves, violent oxen, and flying dragons, which all promote to gold generals), 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. 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. (The pieces are not differentiated by color; the traditional chess terms "Black" and "White" are only used to indicate who plays first, and to differentiate the sides during discussions of the game.) 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 (or 先手
sente and 後手
gote), play on a board ruled into a grid of 15
ranks (rows) and 15
files (columns) 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 (most to least powerful) they are: • 1 King • 1 Queen • 1 Lion • 2 Dragon kings • 2 Dragon horses • 2 Rooks • 2 Bishops • 1 Kirin • 1 Phoenix • 2 Violent oxen • 2 Flying dragons • 1 Drunk elephant • 2 Blind tigers • 2 Ferocious leopards • 2 Gold generals • 2 Silver generals • 2 Copper generals • 2 Angry boars • 2 Cat swords • 2 Vertical movers • 2 Side movers • 2 Reverse Chariots • 2 Lances • 2 Knights • 2 Evil wolves • 2 Iron generals • 2 Stone generals • 2 Go-betweens • 15 Pawns 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. (Sometimes the queen is called the "free king", a direct translation of its Japanese name. The kirin's name is sometimes anglicised as
kylin.) 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. :1 The pronunciations of 龍馬, 奔王, 反車, and 白駒 are irregular. The regular forms ''ryūme, hon'ō, hansha,
and hakuku'' are also seen.
Setup Below is a diagram showing the initial setup of the board. The queen could also be abbreviated
FK (for free king) and the kirin as
Ky (for kylin).
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 (that is, forward, backward, left, or right, in the direction of one of the arms of a plus sign,
+), or
diagonally (in the direction of one of the arms of a multiplication sign,
×). 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 (2) of free (empty) 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 (promoted dragon king and dragon horse) 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 only promote if it makes a capture. This is reset by leaving the zone and reentering: promotion is possible on such a reentry even without 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 (because of the lion-trading rules in chu shogi), 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" (死に駒). 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.
The Chess Variant Pages suggest that these differing promotions in chu shogi are a later historical innovation, and that originally the weak pieces in chu shogi all promoted to gold (like in standard shogi). After removing the weakest pieces, the copper general, silver general, gold general, and ferocious leopard may have been considered to be still too insignificant, and were reassigned promotions to pieces in the initial setup that could not yet be obtained by promotion. This innovation would then have been copied back into dai shogi later, 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 gray 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' ("vertical", interpreted relative to the piece's current position on its path). 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[aK] would denote a piece that can move as a dabbaba, or twice as a king.
The jeweled general goes to the inferior player. Step: It can step one square orthogonally sideways. (WfbR) Step: It can move one square vertically. (WrlR)
An iron general can only reach a fraction of the board. An iron general that reaches the farthest rank is trapped. (fK)
A stone general can only reach a fraction of the board. A stone general that reaches the farthest rank is trapped. (fF)
A knight that reaches the farthest rank is trapped. (ffN)
A lance that reaches the farthest rank is trapped. (fR)
If your opponent has a prince in play, both it and the king must be captured to win. Step: It can move one square sideways or along one of the four diagonals. (fbRK)
Because it cannot move orthogonally, an unpromoted bishop can only reach half the squares on the board. (B)
Because it cannot move orthogonally, an unpromoted cat sword can only reach half the squares on the board. It can continue after a capture on the first step, potentially capturing two pieces on each turn. By moving back to its starting square, it can effectively capture a piece on an adjacent square without moving. This is called 居喰い
igui "stationary feeding". A similar move without capturing leaves the board unchanged, which is a way to pass a turn. Jump: The lion can jump anywhere within two squares. This is equivalent to jumping in any of the eight diagonal or orthogonal directions, or making any of the jumps of a knight in Western chess. The capture rules in chu shogi do not apply in dai shogi. The lion does not promote. (KNADcaKmcabK) Jump: It can jump to the second square in one of the four diagonal directions. (WA) Jump: It can jump to the second square in one of the four orthogonal directions.
Because of its unusual movement, an unpromoted kirin can only reach half the squares on the board. (FD) Step: It can move one square in any diagonal direction. (FR) Lion move: It can move or jump one or two squares along either forward diagonal, potentially capturing two pieces. This power includes
igui and skipping a turn (see "Lion"), but
not moving off the diagonal. (RbBf[avF]fA) Step: It can move one square in any orthogonal direction. (WB) Lion move: It can move or jump one or two squares along a line directly forward, potentially capturing two pieces. This power includes
igui and skipping a turn (see "Lion"), but
not moving off the orthogonal. (BrlbRf[avW]fD)
Because it cannot move orthogonally, an unpromoted bishop can only reach half the squares on the board. (B) Step: It can move one square in any orthogonal direction. (WB) Step: It can step one square orthogonally sideways. (fbRW) Step: It can move one square orthogonally forward or backward. (WrlR) Step: It can move one square in any diagonal direction. (FR)
A pawn that reaches the farthest rank is trapped. (fW)
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 (千日手
sennichite). Note that certain pieces have the ability to pass in certain situations – a lion, when at least one square immediately adjacent to it is unoccupied; a horned falcon, when the square immediately in front of it is unoccupied; and a soaring eagle, when one or both of the two squares immediately diagonally in front of it are unoccupied. (The horned falcon and soaring eagle also cannot skip a turn if they are on the last rank, and those squares would fall off the edge of the board; at least, that is the modern rule in chu shogi, and dai shogi should be similar.) 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. However, evidence from chu shogi problems suggests that this at least does not apply to a player who is in check or whose pieces are attacked, as otherwise one could win via
perpetual check or perpetual pursuit. The modern chu shogi rule as applied by the Japanese Chu Shogi Association (JCSA) is as follows, and presumably dai shogi should be similar. If one side is making attacks on other pieces (however futile) with his moves in the repeat cycle, and the other is not, the attacking side must deviate, while in case of checking the checker must deviate regardless of whether the checked side attacks other pieces. In the case of consecutive passes, the side passing first must deviate, making turn passing to avoid zugzwang pointless if the opponent is in a position where he can pass his turn too. Only the fourth repetition is forbidden by these rules. If none of these are applicable, repetition is a draw.
Check and mate When a player makes a move such that the opponent's only remaining royal (king or prince) 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. Thus a player who is
checkmated or
stalemated will lose. The very artificial situation of a smothered stalemate, where no moves are possible (even those that would expose the king), is not covered in the historical sources.
The Chess Variant Pages rule this as a loss for the stalemated player, for definiteness. 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. (This rule may be relaxed in casual games.) == Game notation ==