I just saw that Pathway into Darkness is available in the Mac App Store:
itunes.apple.com/app/pathways-into-darkness/id617234634?mt=12 (Free)
Now I wonder, what else got ported or remade or whatever to run on OS X?
First thing I think about is Aleph One to play the Marathon series:
marathon.sourceforge.net
Anything else?
(I'm talking about the Mac only games or games that were popular on Mac but not so much on other platforms)