DescentBB

I'm wondering what are some single player (Possible co-op, if I could ever find anyone who likes teamwork like that...) campaigns that are good.

The last one (YEARS ago) that I played you got some sort of weapon that was modded. I believe it was for Descent 2, but don't remember much else about it.

I saw the one on the D2x and will try that one. I'm wondering if anyone else has any recommendations?

Maybe I'm just odd, but I don't enjoy killing off others. I like the teamwork stuff.

I used to design levels requiring co-op play. i.e. One player would trigger a switch or door so the other player could go through, split paths, etc. Though most of that has long been gone.

You want Descent 2?

Then a few I could recommend...
Entropy Experiment
Entropy 2 (fairly notable for having pioneered custom models in D2)
Project: Mandrill (maybe Phobos Encounter as well, but I didn't play much of it personally)
Encounter at Farpoint 2: Dimensions (and probably its predecessor)
Obsidian
The Apocalyptic Factor (yeah, it's a bit of a plug, but ya know...)
Bahagad Outbreak
Descent 1: The Lost Levels (big, really big)

There are plenty of others, of course, but the quality can be variable. I might have missed some good ones though.

Nostromo, it's just one level, but it should keep you busy for some time, depending on your navigation skills.