It is a nice little game which is quite pleasant to play.
Overall I didn't really feel the need to use the rewind function, and found that avoiding the enemies was just faster.
Also, I didn't like that the player was so "floaty". It was hard to avoid projectiles once in the air. There is a GDC talk: Building a better jump, that gets into details of how to implement a, well, better jump.
Good job on your first game!