It's a pretty cool concept for a game, but it was sometimes annoying to do the level for the first time knowing that I was going to die anyway. I didn't notice the blood stains at first but they were helpful in remembering where I died which was nice. I also don't think the rewind mechanic fits perfectly, because you could have made the same game without the rewind, instead just replaying the player's movements exactly as they made them. But that's just a theme issue, and to be honest you implemented the rewind pretty well. Congrats!