An old version working under DOS that comes with its own graphical interface. Its playing strength can be tuned so it should be an interesting opponent for beginners as well as for advanced club players. Its strength is about 2100 Elo at blitz time control.
The latest version, totally rewritten and sometime updated. Its playing strength is close to 2700 Elo and makes it a tough opponent for the strongest human players and for the best commercial chess programs as well. It commes with no graphical interface. The engine can be used in text mode or with a Graphical User Interface supporting the Winboard protocol like Winboard or Arena.