Multi Theft Auto is a game engine
fheroes2 is a recreation of Heroes of Might and Magic II game engine
Cocos simplifies game creation and distribution with Cocos Creator
The game engine for everyone
Cross-Platform C++ 2D/3D game engine
Voxel game-creation platform with easy modding and game creation
Powerful, mature open-source cross-platform game engine for Python
Open-source engine for Heroes of Might and Magic III
dhewm 3 main repository
Solar2D Game Engine main repository (ex Corona SDK)
A game engine with an emphasis on real-time cutting-edge solutions
Cross-platform 2D and 3D game engine with modular architecture
Voxel game engine in C++ with OpenGL
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
RPG Maker 2000/2003 and EasyRPG games interpreter
Open 3D Engine (O3DE) is an Apache 2.0-licensed multi-platform 3D
Open source clone of the Age of Empires II engine
The ioquake3 community effort to continue supporting/developing id's
Recreation of the classic Grand Theft Auto III game executable
A multi core friendly rigid body physics and collision detection lib
Descent 3 by Outrage Entertainment
3D Procedural Game Engine Using OpenGL
Multi-platform 2D and 3D game engine
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
3D Game engine with editor