GAMESS for the Apple Macintosh
Apple systems with G4 or G5 processors can run the Mac OS X system, which is a fully functional Unix operating system. GAMESS runs on these like any other 32 bit Unix system, and in fact you can install a source code copy on your system, by backing up one page and requesting the source code distribution. However, if you are not comfortable with using compilers, ask for the binary executable for Apples running OS X when you fill out the registration form.
For G3 systems, or if you are still running MacOS 7-9, there is a fully functional sequential implementation created from an older source code of GAMESS (namely the Sept. 6, 2001 (R2) release) running native on the PowerMacintosh running MacOS 7-9. Request MacGAMESS when you fill out the registration form.