One of my favorite things to do on a game is to sketch out a map of the world. Usually the game world comes to me before anything else. Maybe its because I am an environment artist by trade but I think it has always been the worlds that have drawn me into games.
Even when I think back to the pen and paper games I would play with my buddy Issac it was always the worlds that jumped out at me as the interesting part. At the time I would spend so much time imagining the worlds but for some reason spent all of my time drawing the characters and creatures. In fact when I first went to art school I thought I would be a character artist and not an environment artist. Oh the folly of youth.
The old Squaresoft Snes RPG games had some of my favorite gaming worlds as well as every single Lucas Arts adventure game. A mighty nod to the Sierra games such as Roger Wilco and Kings Quest too. I need to spend more time thinking about my game worlds then I currently do.