Not bad. The idea and basic execution were solid, and the music selected fit nicely.

Acceleration on the player seemed a little low for an arena shooter like this - it makes it hard to intentionally avoid things, so I kept to circling and hoping I didn't run into anything. Because pinpoint maneuvering was too difficult, I ended up not really using the asteroids at all, which is too bad as I think they would otherwise add a neat tactical component.

I also encountered a bug where an enemy spawned outside the map. I happened to die on that wave, but I believe I would have been stuck had I killed the others.

I like the mechanic, it actually played nicely. Of course some polishing on certain aspects, like the above comment pointed out, would help, but overall I enjoyed the concept and the game!

The controls could probably use a bit of touching up, and it was somewhat disappointing to have a map that was limited to 'edges' of the universe when it feels like a game that could have worked just as well with a fully looping map.

For that many enemies with that much health, the controls definitely should have been tighter, though, as I found more than half of the challenge of the game was kind of getting Earth to go where you wanted it to go. Most of the time, when enemies would land a hit, it often came from offscreen so it also often led to trying to fight a lot of things I couldn't even see, which becomes sort of an issue when multiple targets come into play. Probably better for them to wait to fire until they get within range of you, but the player will still need a bit more mobility to be able to dodge incoming fire that triggers within that range.

Otherwise, though, good stuff here, and I did find it enjoyable.