Xash3D FWGS engine
The HTML5 Creation Engine
Fast and lightweight JavaScript game engine built on WebGL and glTF
Open source clone of the Age of Empires II engine
An easy to use 2D HTML5 game engine written in TypeScript
The Tiny JavaScript Game Engine That Can!
A dead simple 2D game engine for Go
Open source library for creative expression on the web, desktop, etc.
GemRB is a portable open-source implementation of the Infinity Engine
Orx: Data-Driven Game Engine
Javascript library for making tile based games
A cross platform Lua based game engine
Cross-platform 2D game engine