The controls are super snappy, which is really nice. I'm not sure if I need other players to play multiplayer with to "play it right" since there doesn't seem to be any sort of score or way to win by killing the enemies that spawn, but it definitely gives those retro shooter vibes right, and the sound effects and font are done well. A couple small things I'd like to see are immunity frames (so you can't lose 2-3 life at once if multiple shots hit you at the same time), and/or some kind of radar that shows where enemies are to make them easier to hunt down (or avoid). :)
I agree that I really do like the controls. I also quite enjoyed the art style and felt everything looked really polished.
I also found that there were no other players online so I wasn't able to really progress. I think that perhaps offering small quests such as killing a certain number of enemies in the lobby to unlock a cosmetic (such as changing the ship's colour, etc.) might help to make that wait better.
Would you also consider making a single-player version?