I loved this! The style, the animations, the challenge, and it's damn simple with few patterns while still being a real pain in the back. I'd suggest to publish this on Steam for free, and adding more bosses with the same style, maybe making those paid DLCs, for example a treant-like enemy with "roots" or "growth" or smth instead of "heat", a water-type boss, a lightning-type one, a rock-type one, there is so much that can be done in this kinda-boss rush game and I love it. Would buy more bosses if this was on Steam and there were! Could also be nice to put leaderboards in there.
Great work.