Clobber is a game invented in Halifax by Michael Albert, J. P. Grossman
and Richard Nowakowski.
The first competitive Clobber tournament was held at Dagstuhl, Germany, in February 2002.
Clobber is played by two players, white and black, on a rectangular n x m checkerboard.
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.
Erik Demaine and Martin Demaine of the Massachusetts Institute of Technology,
and Rudolf Fleischer of the Hong Kong University of Science and Technology have studied a solitaire version of Clobber.
The rules of the solitaire game are exactly the same, but the white and black players play as a single player.
The goal is to remove as many or few stones as possible from the board by alternating white and black moves.