Games Development Engine: Unity
by The EditorUnity is a 3D games authoring engine available for Mac OS X and Windows.
From the Unity website:
The simplicity of professional authoring, the power of a modern 3D game engine. Download Unity now!
Build rich 3D games with animated characters, sizzling graphics, immersive physics. Deploy to Macintosh and Windows as standalone, for the web, or as a Dashboard Widget.
Use JavaScript, C# or Python to script complex interactivity without worrying about performance. Learn from good documentation and loads of examples and tutorials. Enjoy using the features in a crisp pro-application user interface.

