Façade:
Now available for Mac OS X! If you haven't played this, and you have a
beefier machine, you really owe it to yourself to download it. It's free.
You'll either love it or hate it. Play it several times, since the game
changes a little (or drastically) every run.
The requirements say you need a 2.0GHz machine, but people with dual
processors can go lower (I've had successful runs on a dual 1.0GHz G4
system...this game benefits from multiple CPUs more than most!).
http://icculus.org/news/news.php?id=3365
I patiently await Blake Buck's video review. :)
--ryan.