: It doesn't take long to notice this is Yet Another Vacuum Map. I hate those.
I'm convinced they used vacuum so often to weed out any TC players running with the Caps Lock key. On Total Carnage (but not on lower difficulties), your oxygen depletes twice as fast when you have the Run key down, even if you're not actually moving. (Aleph One's "swap run and walk" setting will also drain your oxygen faster, since it just presses the Run key for you.) Since you don't run twice as fast as you walk, you can save the most oxygen by only running when you need to escape from enemies (or deal more punching damage, or turn faster... hmm...).
On Major Damage and Total Carnage, you also lose more oxygen when either weapon key is down. For slow weapons like fists, you can save O2 by tapping the fire buttons rather than holding them down. Just imagine how awful a map would be to give you just enough oxygen to reach the end, as long as you didn't run or shoot...
