The board extends endlessly in every direction. Use the arrows to pan the view, or ● to recenter on your own pieces. Pieces move exactly as in ordinary chess, just never stopped by a board edge (slides are capped at 40 squares for practical reasons).
Infinite Chess is the boardless variant studied by mathematicians — same piece movements as ordinary chess, but with no edge to stop a rook or queen's slide (here capped at 40 squares per move for practicality). The starting position is the ordinary chess array, so early play feels much like a normal game, but pieces are free to run out into open territory in ways a bounded board never allows.
Simplifications: check and checkmate are not enforced — capturing the king directly ends the game on the spot. Castling and en passant are omitted.