The Superpowers HTML5 game engine is now open source and available on Github. In the developers own words, Superpowers is:
Superpowers is a downloadable HTML5 app. You can use it solo like a regular offline game maker, or setup a password and let friends join in on your project through their Web browser. It's great for working together over long periods of time, for jamming over a weekend, or just for helping each other out with debugging!
... not just for making games!
We've built the Superpowers Game engine and a bunch of asset editors to make games with TypeScript. But the coolest thing is this: Superpowers itself is actually engine-agnostic. It's just a piece of software for collaborating on projects and you can extend it with project types and editors.
Use Superpowers to make static websites, Lua LÖVE games, slideshows, blogs, movies... whatever you can come up with!
There is a pretty solid set of tutorials and documents available here should you require more information. You can see a demo of SuperPowers in action in the video below. WARNING!!! Mute your sound, trust me.