You're breathtaking!. I'm always dying after reaching level 4 and a half .
At first I didn't like the controls too much (was expecting mouse for aiming), but after some tries a realized its part of the maneuverability of the ship, offering something not so generic as aiming with the mouse, and leaving room for the players to improve.
The destructible terrain is nice (marching squares? :D), one important thing the game is missing and you're probably aware of due to lack of time is some type of feedback when things happen, be it particles, sounds, etc. After this is added it will improve a lot.
Perhaps could be cool to indicate the position where you're going to rewind every moment. It would give it some more utility.
Overall , I enjoyed the time I was playing, great job!