Grit Game Engine - The Grit Game Engine is an MIT-Licensed Open Source Game Engine that is highly scriptable via Lua.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Pygame - Pygame is a set of Python modules designed for writing games.
ZBrush - ZBrush is a digital sculpting and painting software solution.
Cinema 4D - Cinema 4D is a 3D modeling, animation, motion graphics and rendering application.
Unigine - Unigine Engine is a proprietary cross-platform middleware, developed by Unigine Corp.