For the future reference…
Free game engines for creating point-and-click adventure games:
- Adventure Game Studio (Editor in Windods; Engine for Windows, Linux, and OSX)
- Wintermute Engine (Windows)
Commercial game engines for creating 3D Games:
- Torque3D ( Editor in Windows?; can used to publish for OSX, Windows, Linux, Wii, and XBox360)
- Unity3D (Editor in OSX; can used to publish for OSX, Windows, Wii, IPhone)
- Quest3D (Windows only?)
I have only hands on experience with Unity3D. We are using it for building Lies and Seductions, a game relatting to my doctoral research. So far, I am quite happy with Unity3D.
Petri Lankoski 
The Ultimate 3D-Engine List: http://www.3d-design.0catch.com/3denginelist.htm
Panda3d: http://panda3d.org/, runs on Linux and Windows.
Uses Python as programming language.