Really interesting game!
As mentioned before on stream, the biggest thing for me was really the sfx during the boss battle being especially jarring, and I had to turn off the sound entirely to deal with the boss.
I did notice that there was never an incentive to NOT pick up all the weapons in a room so perhaps it might be interesting to have a puzzle where the player must purposefully avoid weapons initially to set up a room before coming back round.
I did very much like the last room puzzle, and thinking back to it, I think one of the reasons I preferred it to the room with all the barrels was because there were no gaps in the floor that forcefully reset the room.
I also feel the weakest element in the game right now is probably the player character. I don't think I find his personality very compelling or interesting for whatever reason. The boss character on the other hand seems a lot more interesting.
All in all, I liked it.