Cross-Platform C++ 2D/3D game engine
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
Free game engine for development of desktop, mobile, and web games
Voxel game-creation platform with easy modding and game creation
3D game engine with lua scripting
3D Game engine with editor
Doom-based AI research platform for reinforcement learning
Cross-platform real-time strategy game (3D)
A free 3D game engine to create games and realtimes scenes for Windows
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
3D C++ Game Engine - yet another open source game engine
Cross-platform 2D and 3D game engine
3D-Accelerated open-source DOOM engine
EDGE is an advanced DOOM source port
A 3D Game Framework
3d Reversi game
Turn based Civ-like strategy game
A cross-platform, 3D interpreter to play LucasArts' Lua-based games
action/combat flight sim