The gameplay of this game is very nice, it feels good, I'm missing some sound effects to give feedback to the player when somethin occurs. Also, I'd add some depth to the rewind mechanic, right now is very secondary. It's very cool to see bullets rewinding too, but it's strange to see how only some of them rewind (the ones out of screen or not destroyed). If you add sounds and improve the rewind mechanic this could be a very good game. Overall, great job, I've enjoyed the time invested playing it.