Antichess, also called Losing chess and Suicide chess is a chess variant in which the objective is to lose all of your pieces.
We present here the most widely played variation, as described in the book "Popular Chess Variants" by D. B. Pritchard.
The rules of the game are the same as those of chess except for the following additional rules:
Capturing is compulsory.
When a player can capture, but has different choices to capture a piece, he may choose among them.
The king plays no special role in the game, i.e,
It be captured like any other piece.
There is no check or checkmate.
Castling is not allowed.
Pawns may also promote to King.
In the case of stalemate, the winner is the player who cannot make any move.
A player wins the game either by losing all her pieces or by forcing the opponent to stalemate her. The game might be drawn, apart from move repetition or mutual accord, when it is impossible to get a win. For example, a dark squared bishop against a white squared bishop.
The FICS uses a variant in which the player with the lesser number of pieces wins in the case of a stalemate. This is usually the player that is unable to move, so this rule difference rarely affects the outcome of a game. In another little-played version, the goal is to force your opponent to checkmate your king.
Because of the forced capture rule, antichess games often have a long sequence of forced captures by one player. This means that a little mistake can ruin the whole game. Losing openings are 1.b4, 1.d3, 1.d4, 1.e4, 1.f4, 1.h3, 1.h4, 1.Nf3 and 1. Nc3. (See algebraic chess notation). Some of these openings took months of computer time to solve, but the wins against 1.d3, 1.d4, and 1.e4 consist of a single series of forced captures, and can be played from memory by most experienced players.