variant.rst

Variants

python-chess supports several chess variants.

>>> import chess.variant >>> >>> board = chess.variant.GiveawayBoard()

>>> # General information about the variants. >>> type(board).uci_variant 'giveaway' >>> type(board).xboard_variant 'giveaway' >>> type(board).starting_fen 'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1'

Variant	Board class	UCI/XBoard	Syzygy
Standard	chess.Board	chess/normal	.rtbw, .rtbz
Suicide	chess.variant.SuicideBoard	suicide	.stbw, .stbz
Giveaway	chess.variant.GiveawayBoard	giveaway	.gtbw, .gtbz
Antichess	chess.variant.AntichessBoard	antichess	.gtbw, .gtbz
Atomic King of the Hill Racing Kings Horde Three-check Crazyhouse	chess.variant.AtomicBoard chess.variant.KingOfTheHillBoard chess.variant.RacingKingsBoard chess.variant.HordeBoard chess.variant.ThreeCheckBoard chess.variant.CrazyhouseBoard	atomic kingofthehill racingkings horde 3check crazyhouse	.atbw, .atbz

chess.variant.find_variant

Game end

See chess.Board.is_variant_end(), ~chess.Board.is_variant_win(), ~chess.Board.is_variant_draw(), or ~chess.Board.is_variant_loss() for special variant end conditions and results.

Note that if all of them return False, the game may still be over and decided by standard conditions like ~chess.Board.is_checkmate(), ~chess.Board.is_stalemate(), ~chess.Board.is_insufficient_material(), move counters, repetitions, and legitimate claims.

Chess960

Chess960 is orthogonal to all other variants.

>>> chess.Board(chess960=True) Board('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1', chess960=True)

See chess.BaseBoard.set_chess960_pos(), ~chess.BaseBoard.chess960_pos(), and ~chess.BaseBoard.from_chess960_pos() for dealing with Chess960 starting positions.

Crazyhouse

chess.variant.CrazyhousePocket

chess.variant.CrazyhouseBoard

Three-check

chess.variant.ThreeCheckBoard

UCI/XBoard

Multi-Variant Stockfish and other engines have an UCI_Variant option. XBoard engines may declare support for variants. This is automatically managed.

>>> import chess.engine >>> >>> engine = chess.engine.SimpleEngine.popen_uci("stockfish-mv") >>> >>> board = chess.variant.RacingKingsBoard() >>> result = engine.play(board, chess.engine.Limit(time=1.0))

Syzygy

Syzygy tablebases are available for suicide, giveaway and atomic chess.

>>> import chess.syzygy >>> import chess.variant >>> >>> tables = chess.syzygy.open_tablebase("data/syzygy", VariantBoard=chess.variant.AtomicBoard)