Great to see Superpowers making progress. I'm interested in your choice of Three.js. Did you consider other WebGL game engines? Like PlayCanvas[1] (where I'm a co-founder) which is also open-source[2] but more designed towards games than three?
We went with Three.js because it's pretty versatile and does everything we need in the near future. Superpowers is built in 3 layers: the core (which handles projects, storage and networking), the system (which is basically Three.js + game instance/actors/components) and all the editor & asset plugins built upon the system. The system can be swapped out with something else, and a new set of plugins can be built on top of it, or the existing plugins adapted for a new engine, so the community will totally be able experiment with other engines including PlayCanvas!
We spent a lot of time designing the Superpowers platform so that this would be possible :). In fact, Superpowers could even be used to make movies or write novels collaboratively, with the appropriate system and set of plugins.