What is Annan Shogi?
Annan shogi uses the standard board and pieces with one new rule. A piece that has a friendly piece directly behind it moves like the piece behind it, not like itself. A pawn backed by a rook slides like a rook; a gold general backed by a knight jumps like a knight. When the piece behind moves away, the piece in front moves normally again.
The rule applies to every piece, the king included, and it counts for captures and checks too: a king is in check when an enemy piece, moving like the piece behind it, could capture it. Only friendly pieces lend their moves; an enemy piece behind has no effect.
The starting position differs a little: the pawns in front of the rook and the bishop start one row further forward. Building chains of pieces and breaking the opponent's chains are the heart of the game.
Rule changes
| Rule | Standard Shogi | Annan Shogi |
|---|---|---|
| Starting position | Standard ShogiAll nine pawns on each player's third row. | Annan ShogiThe same, except the pawns in front of the rook and the bishop start one row further forward. |
| Movement | Standard ShogiEach piece always moves in its own way. | Annan ShogiA piece with a friendly piece directly behind it moves like that piece, promoted or not. The king borrows moves this way too. |
| Check | Standard ShogiA king is in check when an enemy piece attacks it. | Annan ShogiThe same, but each enemy piece attacks with the moves it borrows from the piece behind it. |
| Promotion | Standard ShogiPawns and lances on the last row and knights on the last two rows must promote, since they would have no move left. | Annan ShogiPromotion is never forced, because a piece can still borrow a move from the piece behind it. |
| Drops | Standard ShogiNo pawn, lance or knight may be dropped where it could never move. | Annan ShogiAny piece can be dropped on any empty square. The pawn rules stay: one unpromoted pawn per file and no checkmate by a pawn drop. |
| How to win | Standard ShogiCheckmate the opponent's king. | Annan ShogiThe same: checkmate, judged with the borrowed moves. |
History
Annan shogi comes from Japan, and its inventor and date are not known for certain. Its name is written with the characters for Annam, an old name for central Vietnam.
Because its one extra rule leaves the familiar pieces and opening in place, it is easy for shogi players to pick up, and it has become one of the most widely played shogi variants, offered alongside Minishogi and Kyoto shogi on online shogi sites.