One thing that fascinates me about these kinds of games is the ability to create your own narrative each time you play the game, depending on how you play it.
For example you could find certain "treasures" or "power-ups" in such an open world that are generated by the game in accordance with what you did in the game in order to find them. This is kind of like taking the idea of achievements (which are usually named in a way that references what you have to do to get them) but instead of giving you meaningless points, rewarding the player with a surprising new gameplay mechanic, or new enemy type or vehicle, or any number of things that feeds directly back into the gaming experience, to create a sort of "on the fly" narrative.
If we could get to a point where the developers would only need to describe the basic building-blocks of these "rewards", and let the game-program generate different combinations of these blocks depending on what the player does, we could create unthinkably many unique gameplay experiences within a common universe, that are each tailored to the person playing and his/her actions during that particular session.
Until you've played it, every game is a system seller!
Wii FC: 4810 9420 3131 7558
MHTri: name=BOo BoO/ID=BZBLEX/region=US
mini-games on consoles, cinematic games on handhelds, what's next? GameBoy IMAX?
Official Member of the Pikmin Fan Club