Thread:Raadec/@comment-3547390-20130307195655/@comment-1496755-20130407144029

Well, the second vent, next to the one that "ejects" you into the Maintenance Hangars, opens a bit later, so you can go back to the previous map :)

The secret with the Mutant is somewhere near those two vents.

And yes - the first level of No Rest for the Living is simply awesome. Very good and modern-looking design, and yet it preserve the classic game spirit.