Grew told him of variations of chess. There was four-handed chess, in which each player had a board, touching each other at the corners, with a fifth… - Isaac Asimov

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Grew told him of variations of chess. There was four-handed chess, in which each player had a board, touching each other at the corners, with a fifth board filling the hollow in the center as a common No Man's Land. There were three-dimensional chess games in which eight transparent boards were placed one over the other and in which each piece moved in three dimensions as they formerly moved in two, and in which the number of pieces and pawns were doubled, the win coming only when a simultaneous check of both enemy kings occurred. There were even the popular varieties, in which the original position of the chessmen were decided by throws of the dice, or where certain squares conferred advantages or disadvantages to the pieces upon them, or where new pieces with strange properties were introduced.