Cute platformer, quite a steep difficulty curve, although I do suck at platformers in general :)
I love the ever-changing palette when you restart a level (and you WILL restart levels many times :).
I have two suggestions if you don't mind: IMHO it's better to use rectangular collision masks for players so you don't end up stuck halfway at platform corners. And maybe you could add some spikes on the ceiling so it's clearer that it's dangerous to jump that high.
All in all, great job guys!