Aww shucks you're making me blush! Thanks so much for your comment! The boss fights were really something new for me, both having multiple boss fights, and how I thought about the Boss's patterns, so I'm glad to hear that you liked them!
I did kind of worry about it not being a "metrodvania" in the sense you mentioned, or the ingredient effects being too uninteresting. I had a second gun planned to tie that and the side effects together, but I had to cut it for time.