I think the speed and scale of the game are really well tailored, as are the projectile speeds - nothing felt out of place there, which is super important for these types of games. It's a game where you can easily get into the flow and just chill out for a long time, which is a very valid way to design a game - if you're not careful you can get hit, but generally the asteroids are random enough that you're not just staying still, but predictable enough that you aren't upset when something ever hits you. The hitbox is large, but I thought that was an interesting way to change it up, it incentivizes active shooting, so that you don't get too passive with just dodging. Since the game advances at a fixed rate, I think changing up the means of progression would be best - it's currently just capped at how many you can shoot infinitely, which isn't necessarily skill based. Various upgrades and time survived might work well - definitely something to experiment with. Overall a satisfying take on a classic arcade game.