I like the colors your chose for your theme!
I'm not sure if it's just me having this issue, but I tried on two browsers to test. (Opera and Firefox) I was walking extremely slow, along with pretty much just flying and going through walls/floors at a bunch of different points. Along with an invisible wall? Not sure if this was intended.
Good bones for a flash style game I would say, but doesn't give me full Gameboy feel visually.