All joking aside (yeah, right!), I could totally envision a game where you start off as the son of the chieftain of a small village. You grow up and your father dies and you become chief. Your goal is to help you village thrive and conquer the neighboring villages and ally them to your village.
Eventually you could build an empire and have RTS elements where you battle other world powers, city-building elements where you have to plan out your capital and also create and maintain supply lines for your empire, and traditional RPG elements where you take control of your original character and go on some personal quest to further benefit the empire.
Am I crazy, or could something like this actually work?