libtwo - All-purpose c++ app prototyping library, focused towards live graphical apps and games
Paraview - ParaView is an open-source, multi-platform application designed to visualize data sets of size...
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.
MOS - Lightweight game engine.
Gmsh - Gmsh is a 3D finite element grid generator with a build-in CAD engine and post-processor.