Godot is a powerful cross-platform game engine
Multi Theft Auto is a game engine
fheroes2 is a recreation of Heroes of Might and Magic II game engine
Open-source engine for Heroes of Might and Magic III
Real Time Strategy game engine supporting early Westwood classics
Xash3D FWGS engine
The Ren'Py Visual Novel Engine
Voxel game-creation platform with easy modding and game creation
Open source clone of the Age of Empires II engine
Descent 3 by Outrage Entertainment
dhewm 3 main repository
The ioquake3 community effort to continue supporting/developing id's
Cocos simplifies game creation and distribution with Cocos Creator
3D Procedural Game Engine Using OpenGL
The game engine for everyone
Open source voxel game engine with support for survival and crafting
Recreation of the classic Grand Theft Auto III game executable
An OpenGL RTS game engine written in C
A game engine powered by python and panda3d
3D Game engine with editor
RPG Maker 2000/2003 and EasyRPG games interpreter
A complete 3-D game development suite written in Java
Fast and lightweight JavaScript game engine built on WebGL and glTF
Solar2D Game Engine main repository (ex Corona SDK)
LayaAir is an open-source 2D/3D engine