GNU Go is a [ext] free go-playing program (engine) (under the [ext] GNU GPL). It compiles on many platforms, including GNU/Linux, Unix, Windows and Mac OS (both classic and Mac OS X).

A graphical go client is not included. To play against GNU Go on your computer you should therefore also install a GUI capable of running GNU Go. Alternatively you could use the text-based ASCII or the [ext] GNU Emacs user interface.