Godot is a powerful cross-platform game engine
Xash3D FWGS engine
Multi Theft Auto is a game engine
The Ren'Py Visual Novel Engine
Open source voxel game engine with support for survival and crafting
The game engine for everyone
A game engine powered by python and panda3d
Open-source engine for Heroes of Might and Magic III
Real Time Strategy game engine supporting early Westwood classics
A complete 3-D game development suite written in Java
fheroes2 is a recreation of Heroes of Might and Magic II game engine
A retro game engine for Python
Solar2D Game Engine main repository (ex Corona SDK)
Voxel game-creation platform with easy modding and game creation
Open source clone of the Age of Empires II engine
Fast and lightweight JavaScript game engine built on WebGL and glTF
Powerful, mature open-source cross-platform game engine for Python
dhewm 3 main repository
The ioquake3 community effort to continue supporting/developing id's
RPG Maker 2000/2003 and EasyRPG games interpreter
Recreation of the classic Grand Theft Auto III game executable
Magic Another Game Engine
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
An OpenGL RTS game engine written in C
Free game engine for development of desktop, mobile, and web games