Fast and lightweight JavaScript game engine built on WebGL and glTF
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
Open source library for creative expression on the web, desktop, etc.
3D C++ Game Engine - yet another open source game engine
2D Game Engine
The Atomic Game Engine is a multi-platform 2D and 3D engine
Turbulenz is a modular 3D and 2D game framework
TurboSphere is an easy to learn and powerful JS based game engine.
Free MMORPG Engine. Develop and host graphical browser-based games.