This concept is great, was really hooked on how unique it was! Simple to understand but super engaging. The art and palette were on point and pleasant to look at - same with audio, the chiptune track felt right at home. Characters and dialogue had a lot of flavor as well.
As some others have indicated, I think it would be cool to get some sort of heads up to what enemies might be dropping in next - maybe something like Tetris where you get a preview of what the next shape will be? Just felt like there were a few scenarios where several things would drop suddenly, which makes kicking stuff to the other side a bit frantic.
Great job on this, was a lot of fun!