There are some cool ideas in here, nice job! I liked the boss variety, it felt like I found at least 4(?) bosses with different attacks. I also really liked how the dash had a tiny hop at the end. I got locked in the room with the ceiling boss, and when I killed it, the invisible wall in the entrance seemed to still be there, so I got stuck after that.
I appreciated how large the map was and how useful it was to go back and look for stuff. I found two health upgrades! The backgrounds and tileset look quite nice as well.
Nice work!