I was going to write something about "What is an RPG?" introductions, but I think I'll mull that topic over a bit longer.
Instead, here's something I've been thinking about: the settlement campaign, as inspired by Dwarf Fortress. I don't mean a campaign with monsters and other details borrowed from Dwarf Fortress; I mean playing D&D with the intent of establishing a functioning settlement instead of robbing tombs or hunting for treasure. The adventuring party, like the embark party in DF's Fortress Mode, is a band of settlers; the object is to establish a colony, get it to self-sufficiency, tame the wilderness.
There's a hint of this in standard D&D. A lord or patriarch builds a stronghold and clears the wilderness around it. But the details of stronghold management are pretty sparse, and seem to be focused more on establishing a tax base and waging wars. I'm talking about a much lower level of play, here.
I'm contemplating how to do this without bogging everything down with bookkeeping. I've got some ideas, but I'm wondering what others have done along these lines.