Definitely a fun game to spend time on! At least for me, whenever I hit the projectiles after a high multiplier the game would "freeze" for a frame or so which made it unreliable for me to hit the next deflects. Otherwise than that, it's a very enjoyable game even though the theme is a bit of a stretch on rewind. The art is great and audio fits well with the game!
For further improvements: Like someone mentioned in the comments, adding obstacles or surfaces which bullets could rebound on would be a fun addition, though it would up the difficulty a little.
Overall, very well done in a week!