Really great entry, with a lot of juice! One of my favorites so far. I think the screen shake/animation could be a bit more subtle when enemies hit the wall (because it gets difficult to see friend from foe.) Some levels had good contrast between friend and foe, but not all. The yellow/green levels were more difficult since the color of the player and enemies were almost the same.
I’d appreciate a checkpoint or more lives because I gave up after loosing the 11th wave when I had to start over. I think this game could be released already, it’s very polished and easy to get into, well done!