Nice game, I liked the music and pixel art, and the particle effects.
I didn't get through too many waves, so I might have missed some content.
The aliens can speed up to pretty crazy speeds if they follow you for long enough, making it very hard to hit them. I noticed there was a bit of knockback when you shoot them, but it's not quite enough to keep them away particularly when they're going fast.
The gameplay feels kind of disjointed because there's two separate things you need to do: fight aliens, and repair parts of the ship. You never have to, say, defend a repaired part of the ship from attacking aliens, or get attacked while repairing.