This is really good!
The day length and oxygen timing is good, I like that oxygen can be replenished from enemies as well.
The controls and enemies are also really well done, I think it would be cool to have the enemies become more difficult as time passes.
I think having the dialogue box disappear after finishing a task would be really nice, it staying makes it seem like a task is not complete.
I'd rate the current difficulty at 5
-Alexis Rivera