Excellent level design! I appreciate how you carefully lead players through the first level to teach them basic mechanics and explain things. The idea is very interesting, because it's fun to watch the objects soaring through the air as you rewind them. Although, when they just lying down the first few seconds after the player hit "R", it feels like the rewind's not working. Maybe you could show a progress bar, for example, to show that the rewind is actually in progress, even if the object is not moving. Nevertheless, good job!