Got stuck on level 6 I think, no idea how to get up those platforms or high enough to get the key. I solved the first few levels instinctively, pretty quickly and barely knowing what I was doing, then I had to think harder once I got to the longer room, though it was fun to do once I got it. It's a nice concept, though maybe it could use a softer difficulty ramp up to get used to the logic and timing and make it a bit more obvious.