Myth III is totally cool in OS X!
The 3D modelling of characters is nice. Wind gusts cause trees and grass to sway, and airborn objects (arrows and Dwarvin Cocktails) to be blown off course. Lot's of new fighting units and enemies. Cool story. I've only played it for about 2 hours so far, but it's been really solid in OS X.
I'm playing it on my Quicksilver 867 with GeForce MX 2. I'll also try installing it on my B/W G3 450 with Rage128, and see how that thing handles it.