Phaser is a free and fast 2D game framework for making HTML5 games
Easy to use Python library for creating 2D arcade games
Lua Virtual Reality engine
Creative cellular automata browser game
Godot game template and component-based framework
An open source library for GPU-accelerated robot learning
2D GPU-accelerated framework for ActionScript developers
Javascript Matrix and Vector library for High Performance WebGL apps
Ct.js is a desktop game engine that makes learning programming fun
Cross platform Virtual Reality authoring and playback
A Logo-like 3D environment, implemented in Nim
iOS and OS X animation library for physics-based interactions
A Phaser CE plugin that brings sloped tile collision handling
Super-fast 3D framework for Web Applications
3D .NET engine for Windows, Linux, Mac
Cocos2d for iOS and OS X, built using Objective-C
2D physics engine and simulation
The Tensor Contraction Engine
A cross-platform OpenGL based lightweight scenegraph library
Box2d Flash Alchemy Port + World Construction Kit