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'

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

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	chess.variant.AtomicBoard	atomic	.atbw, .atbz
King of the Hill	chess.variant.KingOfTheHillBoard	kingofthehill
Racing Kings	chess.variant.RacingKingsBoard	racingkings
Horde	chess.variant.HordeBoard	horde
Three-check	chess.variant.ThreeCheckBoard	3check
Crazyhouse	chess.variant.CrazyhouseBoard	crazyhouse

chess.variant.find_variant(name: str) → Type[chess.Board]

Looks for a variant board class by variant name.

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(), chess960_pos(), and from_chess960_pos() for dealing with Chess960 starting positions.

Crazyhouse

class chess.variant.CrazyhousePocket(symbols: Iterable[str] = '')

A Crazyhouse pocket with a counter for each piece type.

add(piece_type: int) → None

Adds a piece of the given type to this pocket.

remove(piece_type: int) → None

Removes a piece of the given type from this pocket.

count(piece_type: int) → int

Returns the number of pieces of the given type in the pocket.

reset() → None

Clears the pocket.

copy() → CrazyhousePocketT

Returns a copy of this pocket.

class chess.variant.CrazyhouseBoard(fen: Optional[str] = 'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR[] w KQkq - 0 1', chess960: bool = False)

pockets = [chess.variant.CrazyhousePocket(), chess.variant.CrazyhousePocket()]

Three-check

class chess.variant.ThreeCheckBoard(fen: Optional[str] = 'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 3+3 0 1', chess960: bool = False)

remaining_checks = [3, 3]

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)