Nice concept ! I don't know if it's normal, but I could go through a low of ceilings ^^'. It seemed like a bug, since it cheesed some level design.
The concept is basic, but cool ! I find the minimalist design very efficient here, good job ! The music is a bit short, it makes it a bit repetitive. Fortunally, the game is short, so it's ok, but be careful if you plan to do more levels =).
Keep up the good work !