Advices
This game needs balance. There is not enough time for players to get attachment for their weapons and take their real advantage because every level unloacks a new weapon.
The 3rd level needs some optimization, even at the boss battle. There are too much graphic elements (with filters?), causing a lot of framerate decrease.
I liked the art style, indeed they are made of paper. Those bounce effects on the start menus annoyed me, they are unnecessary.