What makes a good computer game? A strong narrative with a protagonist along with elements of jeopardy, drama and surprise... perhaps this is nothing new; just the ancient art of story telling... but games offer more: they take us in, we become immersed as part of the landscape and increasingly we share the experience. The Legend of Zelda, The Secret of Monkey Island.... The Elder Scrolls. There are endless whole worlds out there, made for us to explore.