Crystal Space is an Open Source 3D SDK for Unix, Windows, and MacOS/X. It renders with OpenGL and features GLSL shaders, CG shaders, deferred rendering, dynamic shadows, bullet based physics library, terrain engine, skeleton based animation meshes, exporter for Blender, portals, etc...
Perl bindings to the Modern OpenGL API
The Perl OpenGL 2 module provides bindings to the modern OpenGL APIs for use from the perl language.
Exipnos is an Open Source, network based 3D virtual reality platform. The platform is intended mainly (but not exclusively) for eLearning applications. Role Player or Adventure Games might as well be developed and hosted on Exipnos.
Lamia or Lamia Engine is the modern generation free distributable and open source game engine for creating computer games for several prevailing software platforms and very maybe hardware platforms either.
The Open Descent Foundation (ODF) is a community for developers, who want to help to create open source programs, tools, etc. for the famous games Descent1, -2 or -3. Everyone can join the ODF if he accepts the idea of writing open source programs.
Tidarque is an open source VRML browser for Unix. It intends to be robust, full-featured, flexible and fast (in that order !).
vuVolume is a framework for volume rendering algorithms in C++. When creating a new rendering method in vuVolume it is possible to just concentrate on the actual algorithm and let the framework take care of the more administrative tasks.