I didn't find the game that fun. There's not much challenge, instead you just walk around a maze looking for keys. Having spikes on the walls or enemies would have made the game much better (and put your skills of dealing with the physics to the test).
I really like the atmosphere you set up with the music though. The graphics fit your idea well too, although I think the gradient background is a bit bland. The music instruments did get a bit grating on my ears and I had to turn it down (and ended up still hearing it in my head please help); though I would keep the weird instruments to sound effects and whatnot.
There's not much to write home about for this game, but I see a lot of potential in it.