Injectable LUA scripting system, SDK generator, live property editor
Multi Theft Auto is a game engine
The game engine for everyone
Voxel game-creation platform with easy modding and game creation
Free game engine for development of desktop, mobile, and web games
Cross-platform 2D and 3D game engine with modular architecture
fheroes2 is a recreation of Heroes of Might and Magic II game engine
A game engine with an emphasis on real-time cutting-edge solutions
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
Voxel game engine in C++ with OpenGL
3D Procedural Game Engine Using OpenGL
GemRB is a portable open-source implementation of the Infinity Engine
Orx: Portable Game Engine
RTSish Game Engine
Modified source engine (2017) developed by valve and leaked in 2020
A conservative source port of Wolfenstein 3-D
Vivid is a modern C++ 3D engine using OpenGL4+
3D C++ Game Engine - yet another open source game engine
2D Game Engine
A cross platform Lua based game engine
KlayGE is a cross-platform open source game engine
A fast, scalable, distributed game server engine/framework for C++
Free and Open Game Programming Language for Windows and GNU/Linux