Wow I dig the atmosphere, it was very convincing on that point. I felt like all the four tools were each useful, and the fact that you can open up the tutorial again helps! You were also generous on the oxygene, I finished with like fifteen left, so it didn't stress me out that much.
I thought I would get lost in the level because the level art looks mostly the same everywhere, and it's very dark, but surprisingly I never once got lost and always was going forwards, so great job on that point!
The controller was a bit slow and unresponsive, but I think it also contributes to the global feel of the game. The camera was nice too!
Well done!