Ataxx
Ataxx is a strategy game where you try and dominate the board by replacing your opponents pieces with your own. The game is a relative of other disc-flipping games such as Iagno. Ataxx, however, begins at the corners, rather than at the center of the board, and has slightly different rules for adding and moving discs.
Ataxx has now been removed from gnome-games 2.17.x, and is only available in the gnome-games-deprecated CVS module.