IC: Defend your town from Underdark threats (4E)
I'm thinking about a 4th Edition D&D game in which the growth and existence of the PCs' town is threatened by several threats stemming from the upper levels of the Underdark. The PCs are among the first crop of capable adventurers in their town, and if they want the town to survive and to advance their own training, they will have to deal with the creatures that have come above ground and head into the dark to stem the growing tide of dangers.
It would be a fairly generic setting, with access to most game sources. Dealing with the threats would involve combat and action, of course, but the goal of the action won't always (or even usually) be about wiping out the other side.