Windows and Macintosh versions.Has just about any option or feature that you would like including 5 skill levels for all levels of player.Gives advice on moves and the doubling cube, can take back moves and doubles of the cube, on-line help, can pick up more than one piece at a time, shows best moves, can set up any board situation, can change board colors or create your own, multiple board sizes, tournament play, extensive help system, keeps statistics on up to 4 pairs of players, can rollout positions plus much more.On my web site you can download versions that work on almost all Windows and Macintosh machines.In this version you will be able to finish half or more of the games.