A good attempt at a boss rush kind of game. The art is by far the best part, although the boss could have a bit more interesting of a design. The gameplay is fine, it suffers a bit due to some repetitive boss patterns. As others have mentioned, audio and visual reactions from the boss would greatly help assure the player they are actually damaging the boss. Finally, there are a fair amount of bugs to fix: boss's heart attack prints to the console (which the player is shown), the performance worsens over time (probably due to bullets not being destroyed and somehow I was able to fall through the floor (probably from a stutter). Also you said looming instead of blooming in the tutorial.