I never have all the files for most of the games in the multiplayer lobby, but I play what I can. I've beaten all the campaigns and the custom ones don't interest me. Occasionally I'll download some addons and make some of my own things in editor. For example, today I made myself part of a LegaMod bomber squadron and attacked a small area filled with a lot of Flak cannons. Most of my 7-plane group went down pretty quickly, but before I got shot down I escaped and killed some people on the ground. Then I was blown up by a Flak. I find these things amusing (I don't know how to make the simplest "walk here and you win" mission, I make do with what I have).
Single player missions, unlike the campaign missions, aren't story driven and thus lose a lot of the appeal for me. I sometimes play the Humvee race one, it's fun.
I think multiplayer gets my vote.
