Cool game, love the art, theme, and the book layouts.
The issues I ran into:
It seems too easy to plan out a safe exit. Without randomized oxygen loss you can just do some simple math to see if you can make it to the exit still or not. I wish the game had a little more luck in it, I testing just rolling a d6 whenever I move and if it comes up as 1 losing 2 air instead of 1.
I haven't played all the scenarios or maybe I missed a rule, so I could be wrong in this. Are you somehow not meant to know what events are coming or how much air it takes to complete a room?
Also the fact that you do not need to place a corridor at the start of the game seems odd. In my first playthrough I didn't do this and I drew the vault as my very first card which ended my game then and there as I need more rooms to actually complete my contract. I don't know if this was intentional, but showing up to a wreck and then turning around and leaving I didn't feel made for a compelling story.
All that said the rules themselves state the player can do whatever they like to improve the experience, which I always appreciate.