Very good implementation! Incredibly scary and anxiety inducing! Great atmosphere!
I guess in the game's predicament taking deep breaths is not the best course of action, since the oxygen supply is low.
By the way, I couldn't figure out if there's an indicator for player oxygen? There's the oxygen supply, and the warning "don't forget to breathe", but I missed stronger indication. Also, I kept trying to read something about Lazarus on the bottom of the screen which I couldn't , because the screen was shaking. I think you definitely reached your goal for the gaming experience, congratulations!