Ct.js is a desktop game engine that makes learning programming fun
Magic Another Game Engine
fheroes2 is a recreation of Heroes of Might and Magic II game engine
Open source clone of the Age of Empires II engine
A fresh & lightweight javascript game engine
Open 3D Engine (O3DE) is an Apache 2.0-licensed multi-platform 3D
Haskell game engine library for roguelike dungeon crawlers
Game framework with AI
Opensource crossplatform Fallout 2 game engine writen in C++ and SDL
Game engine supporting many 3D/2D formats and graphic effects
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
3D playground built on three.js and cannon.js
A space race game in the style of A Dark Room
An online multiplayer turn based strategy game and board game engine.
A Simple Game Engine
A game engine in java for 2D strategy games