You know, I'll probably get mixed reaction or criticism for this, but I think the concept and game of Paper Mario was very well done and executed. It was simplistic, but fully expressive of the elements within a franchise that made it warm and welcoming to just about everyone, all within a simple and enjoyable RPG. I think if done right, it could apply to many other games too, to give a more light, whimsical, yet fun angle on existing franchises.