very nice and impressive project ! this one will definitely go into our gallery :)
As one of the main improvement, I was going to say that a fullscreen option would be great, and easy to add, but then I had the idea to check the source code to see on which version of melonJS it was based, and saw : ............ 0.9.8, that was released in July 2013 :):):) to be honest I would not be even sure where to start if I had to migrate such an old version, so better keep it that way especially if you do not plan any further evolution on it.
Anyway, once again, great project, and thank you for sharing it here !