Cool game! For some reason I didn't die when I hit blocks above me from below. Level 3 was soo hard I couldn't get up that narrow staircase. I think if you changed the walls to something more dangerous like spikes it might be more intuitive to avoid them.

Cool concept, a bit hard to grasp. Maybe you should dilute down the difficulty by adding more simple levels at the begining, people playing your game will be less good at it than you, and might get frustrated fast. This is especially true during a game jam.

The music was kinda annoying after a while ^^'

Well done. Maybe lowering a bit the speed on player may help to make the gameplay more pleasant. It is an interesting concept.