Oh boy, I think there might be a fairly critical bug if you're playing on OSX that causes you to fall through the floor after jumping. Odd that it would only be on OSX; I'd think that the Unity browser plugin would play exactly the same on any platform.
I could've sworn I didn't notice this when playing it on a Windows machine, but we'll see. I'll fix it when I get home either way.
Valuable lessons in platform testing!
Edit: Ok, OSX version has been fixed. While I was in there, some visual improvements were made and the overall robustness of the game increased. There was on occasional bug wherein you could fall through the floor on Windows as well, but it should be fixed for all versions of the game.