Mind-blowing. This was probably the game in this jam that I've played the longest. A few minor issues where the second boss has the collision mask enabled before fully spawned so you can already make damage after entering the room and once you have no more hearts there is no more penalty to collecting anything. I've probably beat the two bosses each around 30 times, kept collecting the attack upgrades until I was able to finish the bosses one-hit with the 50% health reduction, two hits without. I wanted to stop playing around five times and went for my mouse, but then decided - nah, a few more runs!
A few more bosses, a bit of fine tuning and this will be amazing - nevertheless had to give this game full score because I love the art, love the boss behaviour and thought this was a great game. Amazing job on this one!