Clobber is played on a rectangular grid of size m times n. Two players Red (or White) and Black move alternatingly, with Red to start. The last player to move is the winner. Draws are not possible.
 
In his turn a player has to jump orthogonally with one of his stones on a stone of the enemy which is placed on a neighouring square. This piece of the enemy is deleted; it has been 'clobbered'. In each move exactly one stone is clobbered. Players are not allowed to move on free squares!
 
In the starting position the board is completely filled with stones, alternatingly red and black ones.
 
 
A first Clobber tournament (on 6x5-boards) was played during the Dagstuhl workshop on Algorithmic Combinatorial Game Theory in February 2002. During this workshop also the first computer Clobber tournaments were played, on 6x5- and on 6x6-boards.
 
Ingo Althofer wrote a ZRF (named 'Zilly Zillhofer') for Clobber, and it turned out that Zilly is rather strong in Clobber. Especially, in the 6x6-tournament Zilly came in on rank 2, in front of the very fast brute force program 'Deeper Clobber' by J.P. Grossman. The 6x6-computer tournament in Dagstuhl was won by the program 'Bobber' of Bob Hearn (MIT).
 
Professor Elwyn Berlekamp (U Berkeley) from the community of "Combinatorial Game Theory" has announced a CLOBBER PROBLEM COMPOSITION CONTEST. Deadline is on July 20, 2002. Details may be found at http://www.cs.ualberta.ca/~cg2002/an_clobber.html.