Spore will cover the entire landscape of sims. You start as a single-celled critter, eating and trying to not be eaten. As you get to whatever is required to "move up" you get to choose what you want to add, subtract, or change on your creature... you control its evolution. Your creature is not alone, but an entire race.
Once you have grown enough, you move on to land. The dynamics change with the landscape. As you progress, you begin to develop culture and civilization. you move into tribes, and then on toward villages, towns, and cities.
As your civilization matures, you develop technology. Other civilizations are around you, so you must defend or conquer or play the diplomat. You eventually develop space travel, and can go and visit the worlds of other players.
While all of this is going on, your creature is being used in everyone else's world. As you grow and evolve, your creature does the same everywhere else. the game is interactive in that the players share their creations through the game itself.