Godot is a powerful cross-platform game engine
Xash3D FWGS engine
The Ren'Py Visual Novel Engine
Multi Theft Auto is a game engine
Voxel game-creation platform with easy modding and game creation
Fast and lightweight JavaScript game engine built on WebGL and glTF
A game engine powered by python and panda3d
Open source voxel game engine with support for survival and crafting
dhewm 3 main repository
Real Time Strategy game engine supporting early Westwood classics
The game engine for everyone
fheroes2 is a recreation of Heroes of Might and Magic II game engine
The HTML5 Creation Engine
The ioquake3 community effort to continue supporting/developing id's
Solar2D Game Engine main repository (ex Corona SDK)
Recreation of the classic Grand Theft Auto III game executable
Open-source engine for Heroes of Might and Magic III
Powerful, mature open-source cross-platform game engine for Python
A retro game engine for Python
Open source clone of the Age of Empires II engine
LayaAir is an open-source 2D/3D engine
Multi-platform 2D and 3D game engine
Cocos simplifies game creation and distribution with Cocos Creator
Stride (formerly Xenko), a free and open-source cross-platform C# game
3D Procedural Game Engine Using OpenGL