-Nice pixel art, I like the loading animation.
-If not fullscreen, the text on the top of the screen will overlap. Also the sound mixing is a bit off.
-Theme is something else, I kind of like it. Enemies seem pretty good in variety, I liked both bosses. They could stand out a bit better from the background though. I don't like how hard it is to know where my hurtbox is.
Good base of a game, keep it up.