Cool little game.
I have some problem with hitboxes. Because sometimes not really clear when bullet fly under building, and I need time for understanding this mechanic. Some hitboxes on the road, where kaiju. Visually clear but illogical.
All in all. Feeling that art is more important here than mechanics. And it should be the other way around. If you draw everything with a top-down view, you can get rid of some of the problems.
But it's look very good. Keep it up.