Nice game ! I beat the boss first try with 16 HP left. The game design is really good imo. The idea of the 2 slots to protect and the super shot while holding space to switch slots rocks. I really love the music too, nice selection. But I'm not a big fan of the art, I prefer big fat pixels like you saw, but I reconnize the work you put in, it's a very "intimate" art style ,it's just personnal taste dont take bad.
8/10 would first try again ; )