Wow we had pretty similar takes on the theme/controls! I like the fluidity of the movement.
I think the main critique that I'd have is I feel like you could get more out of the movement by having the levels be a bit more open and the camera zoomed out a bit, because the controls feel really nice when you're moving at high speeds and dodging the enemies but the levels almost feel a bit too cramped so you can't quite keep the flow of the movement going
I also really like the music, and the animation of the submarine was cool as well.
That was fun! I did a full play through, and my time was 850-ish which I'll take (I am NOT a speedrunner lol)
good stuff :)