Pachi and fuego are open source engines you can make work on Mac. To play online, IGS is quite nice-looking on Mac, and the most western-populated server is KG

Pachi and fuego are open source engines you can make work on Mac. To play online, IGS is quite nice-looking on Mac, and the most western-populated server is KGS. Ogs is a browser based turn & real time server, too. KGS: Kiseido Go Server IGS: Internet Go Server OGS: Online Go Server