Oh these are really good notes, thanks!
I didn't want to add score pickups to avoid making a lot of visual noise but I think I agree with you regarding how passive it feels, there's a lot of space between waves I wasn't sure how to fix. At least not with twice the number of enemies, or being able to time the waves better. Maybe I'll just put some in and see how it feels.
Scoring in general is something I'd like to make more interesting in another game, since it's finite at the moment and I don't think the highscore even works probably. It certainly doesn't save.
As for bugs, there's probably something I overlooked in the pause menu but I have no idea what causes the bomb button to get stuck. The keyboard controls also get stuck on diagonals. Those are things I'd like to iron out a bit earlier next time. I might be able to fix the mercy invincibility with just another timer though but we'll see.
Thanks again for the feedback!