Really enjoyed the use of multiple audio regions to give a sense of progression as you explored. It is clear that you as a developer appreciate aspects of mystery both in the narrative you crafted and in the game design (exposed yet seemingly unreachable paths, etc.).
As mentioned here otherwise, respawn time could be reduced. I also felt that the game ramps up in difficult a little bit suddenly towards the end, which could be worth looking at.
P.S., the sudden, piercing sound of dying on spikes made me jump: twice LOL