This game is very pretty, the art and audio is very good. The main mechanic is great, although I see 2 flaws in it, a). At the beginning of each round the gap between the first and second shot is longer than normal and b). When you shoot you velocity is reset and not stacked. I see the reasoning for resetting the player's velocity so it's easy to turn around but that means that if you are close to the edge it's almost impossible to escape because you can't move your mouse offscreen. Maybe if the player's velocity would continually increase up to a certain point and would only be reset if the new velocity was close to 180 degrees from the old one.
The system that exists now is fine it just takes time to realize that that's how it works so it is unintuitive for the first few rounds.