I love the boss and his behavior pattern; it's very well done.
At first, I was scared by how difficult he looked and how little health he had, but then everything made sense. I really liked that sense of surprise.
The one-way attack added extra complexity. While playing, I thought about shooting wherever the cursor is pointing. Of course, this would make it easier, but it's an option.
The roguelike style with the variety of items is very good.
What I found interesting and wonderful at the same time is the way dying makes you stronger. The game doesn't frustrate you at all and lets you play and progress freely.
Congratulations for the game! I loved it and had a great time playing it <3