A Basic Babylon.js Game Engine.
The graphics are made with Babylon.js, and the physics with Cannon.js. You can see the result here: https://www.khanacademy.org/computer-programming/babylonjscannonjs-demo/6004235352326144
If you want to open the demo, then download the .zip file in the releases, and run the RunEngine.html on an text editor.