How about a game in teh style of the new FF WiiWare game...
Not obviously called Final Fantasy but in the GC Crystal Chronicles you could build up your stats so you could od things like grow trees or makes weapons depending on which job you had, and in the new title you send people off to do quests for you and you can build a city, how about that?
IE: Zaraff has been sent on quest: "Collect Mushrooms". Zaraff will return with status of quest in: 1hr 57mins.
And with the reward gained from sending Zaraff on this little quest you can make you city larger.

Characters like Zaraff would be NPCs, and you could have several charcters like him. The better your city gets the more people would come to you looking for work...
Etcetera.