Nice! I too just got GMS from the humble bundle, and it looks like you've made some great progress! We still have a week left, though, so if you want to keep adding and tweaking there's plenty of time! I'll come back and rate towards the end. :)
Also, I have a prototype that uses physics and I put it up here on itch.io in HTML5 and it worked fine. Well, it worked about as well as the windows version. Is there a description somewhere about what they do and don't support with HTML5? I don't want to put a bunch of effort into something that's not supported.