Very lovely and extremely claustrophobia triggering for me. I'm glad that running of air just fades back to the start instead of something more horrific.
I would have liked a little more signposting in terms of airpockets and shafts and such - maybe a type of plant that grows closer to light from the surface? Maybe that kind of thing exists and I just haven't picked up on it, but that would add to the sense the roguelike feeling of run progress being measured in knowledge gained.
I dug the audio, though it did start getting repetitive. If I had been taking time to map and actually think about my route (which feels necessary to complete this), I probably would have less of that experience though.