I really dig the concept! Though I found the controls quite challenging. If you turn around too fast, you will skip over some enemies - which kind of makes sense to prevent the players from trying to cheese the game by drawing infinite circles with their mouse, but also punishes people who are not trying to do so and just turned around in the last second. Also my brain felt quite overwhelmed by having a scope that doesn't actually indicates where you're aiming at. I'd imagine using an analogue stick to turn around would feel a lot more intuitive. Lastly I found it quite hard to differentiate the default orange of the ship from the yellow of the soon-to-be-fired canon - you might consider increasing its size temporarily as well to make it more obvious. Or you know, choose more contrasting colors, lol. All in all, fun game with minimal, but polished presentation and a nice variety in levels. :)