I really love the movement in this game. It's a bit rough around the edges at some times, but for a game jam this is incredible!
The only thing I don't like about the game, ironically, is the rewind mechanic. I feel like it breaks the flow of the game. I'd like to go through the entire level, never touching the ground, shooting all the enemies as I go. That feels awesome. But waiting for the rewind to get ammo just stops the game in its tracks. If you are going to continue with this game, I recommend you scrap the rewind mechanic entirely.
If you do want to keep it, I had some issues where the rewinding sometimes kept going long after I released E and sometimes stopped while I was still holding E.
Don't get me wrong, I really like this game. I think you should be proud of what you accomplished in just a week. But to me the rewind mechanic feels crammed in to fit the theme, while it does not fit in an otherwise great game.
I'd really appreciate it if you would have a look at my game as well, and be sure to download the smaller version :D