A modern, cross-platform Quake game engine based on FitzQuake.
Odamex is a free, cross-platform, modern client-server Doom engine
A cross-platform port of Hexen II game.
GLScene Engine for Delphi & C++Builder VCL Windows 32/64
GemRB is a portable open-source implementation of the Infinity Engine
WW2 U-boat simulation
Hardcore 3D space shooter with spaceship upgrade possibilities.
3D modeler, 3D game maker, 3D demo maker
0 A.D. is a free, open-source, cross-platform real-time strategy game.
functions for 2D/3D graphics + realistic driving simulation
Cross-platform real-time strategy game (3D)
Soccer-themed 3D Sokoban Game
3D third person platform shooter
The library needed to make all those games true
Free MMORPG
3D-Accelerated open-source DOOM engine
3D driving simulation based on Open Dynamics Engine
Bot for id Software's Wolfenstein 3D