Open Source Solid Modeling CAD
BRL-CAD is a powerful cross-platform constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing for rendering & geometric analyses, network distributed framebuffer support, image & signal-processing tools.
OpenSource OpenGL Multiplayer Multiplatform Battle Zone capture the Flag. 3D first person tank game. Project has moved to Github: https://github.com/BZFlag-Dev/bzflag
WideStudio is an Integrated Development Environment (IDE) for building window applications in C++, Ruby, Python an Perl for Windows, MacOSX, Linux, FreeBSD, SOLARIS and other unix and BTRON and T-Engine. This is open and free (under MIT/X Consortiun Lice
Smokin' Guns is a GPLv2 licensed first person Western style shooter based on the Quake 3 engine (Id Tech 3) developed by a loosely knit team of developers and artists. This project represents the game engine.
Abysmal is a project that aims to recreate an engine for System Shock 1 and Ultima Underworld that can run those games with the original data files.
SPRING is a real-time surgical simulation system with soft-tissue modeling and networked haptics. SPRING is cross-platform (Unix, Windows, and OS X.) Written in C++ with OpenGL, SPRING reads many common 3-D file formats and supports parallel processing.