Hi, I really enjoyed the game! The level design is really good, the mechanics are simple but interesting. It is definitely a really original take on the theme, though I think that it is a bit of a stretch to call it rewind. But ok, I'll let it slide :)
I actually really like the music though it is simple, but you could add a bit of juice, both with sound effects and screen shake and such. For example, when you kill an enemy, he just disappears. I think you should add a sound effect for it, some screen shake, and an animation. And if you have time, maybe add a body, or make it explode or something. It would really add to the game.
Also, the ceiling (of the level) acts differently to any other ceiling. You just constrain the position of the player but you don't change his velocity. So you can notice that when you jump and hit the ceiling you slide on it instead of falling back downwards.
And lastly, it is a bit weird that you can jump from below and pass through the platforms (not the blocks) but you can't press down to leave them. Just a small touch that you can add and would make it more "logical", I think.
Oh, and one last thing, you could have a small explanation at the start of the game. Even though it is pretty self explanatory, I think it would help.