Godot is a powerful cross-platform game engine
Multi Theft Auto is a game engine
Real Time Strategy game engine supporting early Westwood classics
The Ren'Py Visual Novel Engine
Xash3D FWGS engine
fheroes2 is a recreation of Heroes of Might and Magic II game engine
Open game and rendering engine packed into a JavaScript framework
The game engine for everyone
A game engine powered by python and panda3d
Open-source engine for Heroes of Might and Magic III
A complete 3-D game development suite written in Java
Voxel game-creation platform with easy modding and game creation
Open source voxel game engine with support for survival and crafting
Fast and lightweight JavaScript game engine built on WebGL and glTF
Flax Engine, multi-platform 3D game engine
Multi-platform 2D and 3D game engine
Descent 3 by Outrage Entertainment
Solar2D Game Engine main repository (ex Corona SDK)
A refreshingly simple data-driven game engine built in Rust
Free, cross-platform 2D game engine powered by Haxe and OpenFL
LayaAir is an open-source 2D/3D engine
Free game engine for development of desktop, mobile, and web games
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
Cocos simplifies game creation and distribution with Cocos Creator
The HTML5 Creation Engine