Create Multi-Plattform high-quality 3D-Games with Mac OS X
Unity is a 3D game editor with powerful cross-platform capabilities. Fresh ideas can be mock-upped and tested in a few hours, then developed into commercial grade games using powerful collaboration technology.
I just tried this application recently (they offer a downloadable trial). It's awesome, offers great usability and, if you're a bit comfortable with 3D / game stuff, allows to create games in a blaze.