The ancient game chaturanga spread outward from India along two main paths: a western branch, where it eventually evolved into modern chess, and a northern one, through which it was introduced into east Asia. Sometime around the 10th or 11th century, an early form of xiangqi (“Chinese chess”) was brought to Japan. There, a number of different variants emerged, ultimately evolving in the 16th century into the game nowadays known as shogi or “Japanese chess”.
Shogi uses distinctive pentagonal tiles, inscribed with characters, for its pieces, and is played on a 9×9 board. Some pieces – the king, bishop, and rook1These westernized names are usually used when talking about shogi in English, even though the literal translations of the Japanese terms would be different. – move just like their counterparts in chess. Others are different:
- The gold general moves one space orthogonally, or one square diagonally forward (but not diagonally backward).
- The silver general moves one space diagonally, or one space directly forward.
- The knight jumps one square forward plus one square diagonally forward.
- The lance can only move directly forward, any number of spaces.
- The pawn moves one square directly forward, like in chess – but it also captures one square directly forward, rather than the diagonal capture in western chess.
There are two other big differences from chess. One is promotion. In chess, pawns promote to pieces when they reach the last rank. In shogi, all the pieces except the king and the gold general can promote when they reach the last three ranks, and the promoted pieces have special moves.
- A promoted rook is called a dragon, and can move like a rook, or one square diagonally.
- A promoted bishop is called a horse, and can move like a bishop, or one square horizontally.
- A promoted pawn, lance, knight, or silver general move the same way as a gold general.
The other big difference is in what happens to captured pieces – they are not removed from the game, but rather are retained by the player who captures them, and can be brought back into the game, on an unoccupied space, under that player’s control. This is called “dropping” the piece, and counts as a full move.2There are a few restrictions on this – a piece cannot be dropped into a position where it would have no legal moves, a pawn cannot be dropped onto a column that contains another of that player’s pawns, and a pawn cannot be dropped into a position that results in an immediate checkmate.
Because of the ability to drop in captured pieces, shogi games tend to take longer than western chess. As in most chess variants, the rook is the strongest piece in shogi, but here (as opposed to shatranj or xiangqi) each side only has one rook. However, the starting position allows the rook to move horizontally from the very first move; openings in shogi are typically classified as “static rook” or “ranging rook” openings depending on whether the rook stays on its original file or moves. Much of the strategy in shogi revolves around arranging one’s pieces in a defensive formation called a “castle”, and there are several named castle configurations, with names like “gold fortress” and “bear in the hole”.
Whereas chess was standardized in Europe relatively quickly, and most chess variants are curiosities that are not very widely played, several variants of shogi survived alongside the standard game and remain popular today. These include chu shogi and dai shogi, which use larger boards with more pieces.