Really liked the idea! But it needs more levels. It left me wanting more!
Also, it's kind of hard to understand what to do: a tutorial with a simple challenge to overcome (maybe even simpler than your level 1) would be great.
Otherwise, it's pretty nice! Good job :)
Edit: Maybe constantly showing the velocity vector of the player would be good! It would be an intuitive way of showing the effects of rewinding if you keep it the same while you rewind. Maybe with that you can even do without a tutorial, as it would be easier to understand what you need to do. I think the afterimages of the player's trajectory that you implemented do help with this, but it's not enough in my opinion. But I still stand by my opinion that it's a great game and that I would love more levels :)