Gnu Go

Gnu Go on the Mac is a Classic MacOS GUI wrapper around the open-source GNU Go engine, letting players take on a strong free Go opponent without dropping to a command line. The most polished port is Hideyuki Fujiwara's Mac GNU Go 3.2.3 from 2003, which embeds GNU Go 3.2 inside a native PowerPC app.

The GNU Go Engine

GNU Go is the FSF's free software Go engine, capable of mid-amateur play on a 19x19 board. The Mac wrapper exposes its full strength while hiding the GTP protocol plumbing that the upstream engine speaks natively, so the player just sees a Go board and menus.

Configuration and Play

Before each game the user picks board size (9x9, 13x13, or 19x19), handicap stones, komi, and engine level. During play, analysis modes can show the engine's territory estimates and move evaluations, which makes the app as useful for review as for casual games.

SGF Support

Games can be saved and loaded as SGF files, the standard Go record format, so positions can be moved between Mac GNU Go and other Go software, posted online, or replayed later. Edit mode lets the user set up arbitrary positions for study.

Compatibility

Mac GNU Go 3.2.3 is a PowerPC build for System 7.6 and later, with confirmed working setups on Mac OS 9.0.4 under SheepShaver. An earlier MacGnuGo 0.5 wraps the older GNU Go 2.6 for users on more modest hardware.