Very fun gameplay, the rewind effect is very innovative! The only suggestion would be to allow maybe teleporting between the different checkpoints you've unlocked, or being to save again at one that's already been used. Because right now, if you save at a checkpoint and you have low health and there are no nearby un-entered checkpoints, you're kind of softlocked because you'll constantly re-enter a nearly impossible scenario, especially if there's enemies behind you...

Good game nonetheless