Imaginitve descriptions with some greate imagery, my personal favourite was the stone coral pipes. Very purple prose, but in all the right ways. It fits the theme to a tee. Really evocative desciptions in here - 'doors yawning open', love it!
Not enough treasure for my own taste, especially for OSE.
Some more clues would also help with some of the puzzles. The solutions are a bit obscure, and I’m not sure how the players would get there on their own. I'm not sure where the party would get blood or flesh for the altar in room 3 without it coming from themselves. Though maybe that was the point?
Some bolding throughout the room keys would help with scannability, but overall the text was readable even at the small size, thanks to decent leading.
To run this, I think I’d need to do a solid pass with the highighter, and then maybe add in more signposting for the traps etc.