Xquarto is a board game designed for the X windows environment.
The game is a two-player game, although for the moment, it is only
possible  to  play against  the computer. The board is composed of
4x4 squares and 16 pieces. Each  piece  has four properties: black
or  brown, horizontal  or  vertical, solid  or  hollow,  round  or
square.  This  makes  up  16  possible  combinations  and there is
exactly one piece for each possibility.

   Initially the board is empty. Now the two  players try to place 
out pieces in a way  that  the  opponent  has  to  complete a row, 
column or diagonal  with a common  property (e.g. all black). This
makes  the  opponent lose. The players do not choose what piece to
put but it is rather player 1 who gives  a piece  to player 2, who
then has to place this  piece  somewhere  and  choose  a piece for
player 1 to put somewhere etc.


WWW: http://www.math.lsa.umich.edu/~mattiasj/games/xquarto/