Clobber is played by two players, White and Black, on a rectangular checkerboard, often of size n*(n+1) for some n. However, in the Computer Olympiads Clobber is played on 10x10-boards. In the initial position, all squares are occupied by a stone, with white stones on the white squares and black stones on the black squares. A player moves by picking up one of their stones and "clobbering" an opponent's stone on an adjacent square (horizontally or vertically). The "clobbered" stone is removed from the board and replaced by the stone that was moved. The game ends when one player, on their turn, is unable to move, and then that player loses.