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

Game end

See :func:`chess.Board.is_variant_end()`, :func:`~chess.Board.is_variant_win()`, :func:`~chess.Board.is_variant_draw()`, or :func:`~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 :func:`~chess.Board.is_checkmate()`, :func:`~chess.Board.is_stalemate()`, :func:`~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 :func:`chess.BaseBoard.set_chess960_pos()`, :func:`~chess.BaseBoard.chess960_pos()`, and :func:`~chess.BaseBoard.from_chess960_pos()` for dealing with Chess960 starting positions.

Crazyhouse

.. autoclass:: chess.variant.CrazyhousePocket
    :members:


.. autoclass:: chess.variant.CrazyhouseBoard
    :members: legal_drop_squares

    .. py:attribute:: pockets
       :value: [chess.variant.CrazyhousePocket(), chess.variant.CrazyhousePocket()]

        Pockets for each color. For example, ``board.pockets[chess.WHITE]``
        are the pocket pieces available to White.

Three-check

.. autoclass:: chess.variant.ThreeCheckBoard

    .. py:attribute:: remaining_checks
       :value: [3, 3]

        Remaining checks until victory for each color. For example,
        ``board.remaining_checks[chess.WHITE] == 0`` implies that White has won.

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)