In the computer games of today, the world is flat, the sun rises into the sky and sets, but it's not really there, it's little more than a clever illusion.
In 2012, I will begin developing Project Vex.
The world of Project Vex will be handled by several of Beowulf-cluster style servers, each supporting a different portion of the world. They will overlap, and appear, to the individual player to be seamless. Each server will be a microcosm, and yet linked to the greater world as a whole. When a player reaches the beginning of the overlap between two servers, they begin to load the other server. By the time the player has reached the end of the overlap, the other server will be fully loaded. At this point the data from the previous server will also be discarded (but not before fully entering the new server). The size of the overlap will depend entirely upon the limits of technology available.
Back on track, the world of Project Vex will not simply be a flat map. The world will be a sphere, floating in a vast space. The moon of this world will not simply be a circle in the sky, representing the moon. It will also be a spherical astrological body, and given the right circumstances, a player might find their character standing on that moon looking down upon the world. Just as the moon shall truly exist and actually revolve around the planet (while rotating, itself), the planet will rotate, and revolve around its sun, much farther away, and much larger. The sun will not only be a physical object in space, it will provide this world with its light. There will be other planets as well (not necessarily viable for life). I believe, for simplicity's sake, I will stop with the star system of Project Vex, and the surrounding stars and galaxies will be an illusion.
If you doubt that this will be possible, recall that EVE Online exists, and in 2012, our technology will be leaps and bounds ahead of its current state, just as we are leaps and bounds ahead of 2006.