This was really fun! I like that you used WASD, because simply having to do WS added some difficulty since it's a little awkward to press both. It's a super simple way to slowly increase difficulty and let the user master the controls before increasing the rate of falling asteroids. I really like the consistency in theming and game feel. It all works together very well (music, sfx, graphics, etc.).
I felt like I wanted a little more from the asteroids blowing up. Maybe a little more screen shake or something? Adding a bit more juice to them blowing up would feel a bit more satisfying to me. Visually with the asteroid shake and the music notes exploding out of it works great, though!
This is more of a personal preference, but I did find as things got really difficult that I'd like a little bit of a break as things got really tense and didn't stop. I ended up giving up and letting myself lose because I didn't want to stay in that level of intensity. Again, this is a personal preference and a lot of people enjoy pushing themselves further into that level of intensity. I would have preferred a wave model to give myself a brief break.
Overall this was a really fun game! Great job. This is definitely a game to be proud of.