Glaurung and Scatha are two free chess playing programs for Mac OS X. The main difference between the two is that Glaurung plays normal chess, while Scatha plays hexagonal chess . Unfortunately, Scatha currently only works on PowerPC Macs, while Glaurung works on all Macs running OS X 10.3.9 or newer.
For Windows and Linux users, it is still possible to use Glaurung, but you will need a third-party GUI. For Windows, Arena (free) and Shredder (commercial) are probably the two best GUIs to use. Using Fritz or other ChessBase GUIs is also possible, but not recommended. In Linux, the easiest way to use Glaurung is probably to install XBoard and PolyGlot .
In December 2006, I started working on a complete rewrite of Glaurung. Because of too many other activites competing about my limited spare time, finishing this rewrite has taken a lot longer than anticipated, but the first reasonably stable and feature-complete version is now ready.
The previous stable version of Glaurung. Glaurung 1.2.1 is probably slightly weaker than Glaurung 2, but has a much more entertaining style of play.
Scatha, my hexagonal chess program, is currently not being developed. The GUI was created with the OpenMCL Common Lisp implementation, which does not work at all on 32-bit Intel Macs, and which cannot be used to create graphical applications on 64-bit Intel Macs. I hope to make a new GUI for Scatha some day, but with so many projects competing for my time, I am not sure when it will be done. Meanwhile, I can only offer the (unsupported) PowerPC version.