Sho shogi

The objective of the game is to capture your opponent's king and crown prince (if present) or all other pieces.

Two players, Black and White (or 先手 sente and 後手 gote), play on a board ruled into a grid of 9 ranks (rows) by 9 files (columns). The squares are undifferentiated by marking or color.

Each player has a set of 21 wedge-shaped pieces, of slightly different sizes. From largest to smallest (most to least powerful) they are:

• 1 king
• 1 drunken elephant
• 1 rook
• 1 bishop
• 2 gold generals
• 2 silver generals
• 2 knights
• 2 lances
• 9 pawns

Most of the English names were chosen to correspond to rough equivalents in Western chess, rather than as translations of the Japanese names.

Each piece has its name in the form of two kanji written on its face. On the reverse side of some pieces are two other characters, often in a different color (commonly red instead of black); this reverse side is turned up to indicate that the piece has been promoted during play. The pieces of the two sides do not differ in color, but instead each piece is shaped like a wedge, and faces forward, toward the opposing side. This shows who controls the piece during play.

Listed here are the pieces of the game with their Japanese representation:

English speakers sometimes refer to promoted bishops as horses and promoted rooks as dragons, after their Japanese names, and generally use the Japanese name tokin for promoted pawns. Silver generals and gold generals are commonly referred to simply as silvers and golds.

The characters inscribed on the backs of the pieces to indicate promoted rank may be in red ink, and are usually cursive. The characters on the backs of the pieces that promote to gold generals are cursive versions of 金 'gold', becoming more cursive (more abbreviated) as the value of the original piece decreases. These abbreviated characters have these equivalents in print: 全 for promoted silver, 今 for promoted knight, 仝 for promoted lance, and 个 for promoted pawn (tokin). Another convention has abbreviated versions of the original characters, with a reduced number of strokes: 圭 for promoted knight, 杏 for promoted lance, with promoted silver the same 全 as above, and と for tokin.

Each side places his pieces in the positions shown below, pointing toward the opponent.

• In the rank nearest the player:
  • The king is placed in the center file.
  • The two gold generals are placed in the adjacent files to the king.
  • The two silver generals are placed adjacent to each gold general.
  • The two knights are placed adjacent to each silver general.
  • The two lances are placed in the corners, adjacent to each knight.

That is, the first rank is |L|N|S|G|K|G|S|N|L|.

• In the second rank, each player places:
  • The bishop in the same file as the knight on the player's left.
  • The rook in the same file as the knight on the player's right.
  • The drunken elephant in the same file as the king.
• In the third rank, the nine pawns are placed one in each file.

The players alternate making a move, with Black moving first. (The traditional chess terms 'black' and 'white' are used to differentiate the sides during discussion of the game in English, but are not literally descriptive. In Japanese, the side moving first is referred to as 先手 sente, and the second player is referred to as 後手 gote.) A move consists of moving a single piece on the board and potentially promoting that piece or displacing (capturing) an opposing piece. Each of these options is detailed below.

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 (meaning 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 knight is an exception in that it does not move in a straight line.

If a lance or pawn, pieces that cannot retreat or move aside, advances across the board until it can no longer move, it must promote.

Some 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:

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, drunken elephant, gold general, silver general and the 9 pawns on each side.

The knight can jump; that is, it can pass over any intervening piece, whether friend or foe, with no effect on either.

The bishop and rook can move any number of empty squares along a straight 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.

A player's promotion zone consists of the three farthest ranks, at the original line of the opponent's pawns and beyond (that is, the opponent's territory at setup). If a piece crosses the board within the promotion zone, including moves into, out of, or wholly within the zone, then that player may choose to promote the piece at the end of the turn. Promotion is effected by turning the piece over after it moves, revealing the name of its promoted rank.

Promoting a piece has the effect of changing how that piece moves until it is removed from the board. Each piece promotes as follows:

• A king or a gold general cannot promote, nor can pieces which are already promoted.
• A silver general, knight, lance or pawn, when promoted, loses its normal movement and gains the movement of a gold general.
• A drunken elephant, bishop or rook, when promoted, keeps its normal movement and gains the ability to move one square in any direction (like a king). This means the bishop is now able to reach any square on the board, given enough moves.

If a pawn, knight or lance reaches the farthest rank, it must be promoted, since it would otherwise have no legal move on subsequent turns.

Below are diagrams indicating each piece's movement. Pieces are paired with their promotion. Pieces with a grey heading start out in the game; those with a blue heading only appear on the board after promotion. Betza's funny notation has been included in brackets for easier reference.

When a player makes a move such that the opponent's king or crown prince could be captured on the following move, the move is said to give check to the king or crown prince; the king or crown prince is said to be in check. If a player's king or crown prince (sole one in play) is in check and no legal move by that player will get the king or crown prince out of check, the checking move is also mate, and can effectively win the game.

A player is not allowed to give perpetual check.

A player who captures the opponent's king and crown prince (if present) wins the game, as does a player who captures everything else, leaving a "bare" (or lone) king or crown prince. 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.)

There is one other possible (but fairly uncommon) ways for a game to end: repetition (千日手 sennichite). If the same position occurs four times with the same player to play, then the game is no contest. (Recall, however, the prohibition against perpetual check.)