Magic:The Gathering over LAN or Internet, alone or against another player (need IP of your opponent). The program is the judge : you play with the true rules. Firemox can also emulate another TBS. Written in Java, works on Mac, Windows and Linux.
The BoardGame Tool offers an easy, XML driven interface to implementing boardgames on the computer, with automatic network play, artificial intelligence and robot possibilities. Game rules are encoded in easy-to-learn embedded Python.