GNU Backgammon (gnubg) is for playing and analysing backgammon positions, games and matches. It's based on a neural network. Though it already plays on a very high level, it's still work in progress. You may play GNU Backgammon using the command line or a graphical interface (based on GTK+). WWW: http://www.gnu.org/software/gnubg/gnubg.html