Yay for good droprates here!
I'm not sure I noticed the big key on the ground when I played, but sure looks good! EDIT: Went to check the room and it's in-your-face if you do the puzzle, which I did! ... Note Gemstone Chamber, inform when you actually get a patch out: the treasure room left light wall purple can't be interacted with from the right? Also water light bridges can't be rafted past even if bridge doesn't exist?
Congrats on breaking through a block!