Cool game. Was a bit confused at first as when I got to the door, nothing happened. Thought the pit was a trap, and fell in by accident one time when I noticed the key.
A couple quick tips to help you out in the future: Use a capsule collider for the player character instead of a box collider; I was getting stuck on the ground a lot, and I'm pretty sure that's the reason why. Also, create a "Physics Material 2d," set the friction to 0, and apply that to your character or walls; that will make it so he doesn't stick to walls anymore.
As for the game design, I'd recommend slowing things down a lot. The player moves way to fast to react in time to use the rewind mechanic for enemies and pitfalls.
Overall though, nice job; it's a finished game with some decent art and that's pretty cool.