I posted this in the suggestion forum but they bickered at me and told me to take it here (I don't really see why) but I'm going to do it anyway.
A lot of the vents in NS are weldable. This is good, and bad.
It'd be really nice if you could make it so once the far end was welded, the near end also automatically closed. Why?
Well, for one, it really sucks when a lerk zooms through your base and into the closed vent, where he morphs into a either a gorge (if there's room) and build a few defense towers inside the vent, or into a fade (or into a gorge and then into a fade).
After the three minutes or so it takes to gather the resources and evolve through all this, the marines have the wonderful experience of:
-Getting hit by acid rocket as soon as they spawn
-Getting hit by web as soon as they spawn
I know, I know, "You should have a grenade launcher to counter this."
Well, yeah. But on some vents, the grenades drop harmlessly down, or worse, bounce way down and around the corner. Mines don't work, and neither do jetpacks--it's a waste to send a marine up there when the fade really only has one place to aim in order to kill the marine.
Either way, it's a big drain on the marines to keep fighting and trying at the same time to rid their base of this perpetual annoyance.
At this point, I leave vents open so later in the game, a marine can go from behind to deal with such a nuisance. Which sort of defeats the purpose of welding vents in the first place.