Multi Theft Auto is a game engine
Xash3D FWGS engine
Powerful, mature open-source cross-platform game engine for Python
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
Open-source engine for Heroes of Might and Magic III
Voxel game-creation platform with easy modding and game creation
Open source clone of the Age of Empires II engine
Free game engine for development of desktop, mobile, and web games
Voxel game engine in C++ with OpenGL
An easy to use 2D HTML5 game engine written in TypeScript
Stride (formerly Xenko), a free and open-source cross-platform C# game
The flexible game engine
dhewm 3 main repository
fheroes2 is a recreation of Heroes of Might and Magic II game engine
Solar2D Game Engine main repository (ex Corona SDK)
A pure Go game engine
Descent 3 by Outrage Entertainment
The ioquake3 community effort to continue supporting/developing id's
Recreation of the classic Grand Theft Auto III game executable
A game engine with an emphasis on real-time cutting-edge solutions
The game engine for everyone
Cocos simplifies game creation and distribution with Cocos Creator
The Open Toolkit library is a fast, low-level C# wrapper for OpenGL
Cross-platform 2D game engine focused on ultimate productivity
A .NET ascii/ansi console engine written in C# for MonoGame and XNA