Well done! It's no easy feat to make such a cohesive game - the visuals, sound, and game feel are all in lockstep.
I got to 16K before letting a ship through, as I was able to defend against big waves fairly well - I found that as long as I juked any close ships, I could survive pretty easily. Maybe having ones that split up or need the focused beam to frazzle would help make this more varied. But anyway nicely done!