You got a really original and interesting concept here. I love the retro pixel art and the rotation effect looks really cool. I actually had a lot of fun playing it! I like the fact its different in a unique way from what we know as a boss rush. The only issues I had were mainly that it was a bit confusing at first, it was hard to tell if ringing the bell was actually doing damage to the boss or it was just collecting blue orbs. Anyways, good job!!