There are two different Mac OS X binaries of the Glaurung 2.2 engine:

glaurung-leopard: An universal binary for Intel or PowerPC Macintoshes
running Mac OS X 10.5 (Leopard) or newer.

glaurung-tiger: An universal binary for Intel and PowerPC Macintoshes
running Mac OS X 10.4 (Tiger) or newer.  It is possible to use this
binary in Leopard as well, but this is not recommended, because the
Leopard-specific binary is much faster (especially on Intel CPUs).
