Great game! I really enjoyed the concept. The turret level is way too hard, and this would have been helped if you introduced the turret earlier, or maybe even without the guard, so we would get used to it.
And a pretty minor suggestion, but the box "corpse" (for lack of a better word) was kinda big. I get the idea of making it leave pieces behind, it's a nice touch. I just would make them smaller, less intrusive.
The speed you get when you go out of control was a fun touch. Lining up that last thrust to try and end the level was a fun way to ramp up towards the end.
A really nice entry, good work. You have a promising concept here.