By living game worlds I mean something like Red Dead Redemption, most of the FF games, Far Cry 3, and Skyrim. Versus something like Fallout 1 and 3, Far Cry 2, Oblivion (I guess). Worlds that generally feel dead after some sort of apocalypse basically. The dead worlds rely more on immersion to keep you interested in the world, though it can be quite boring and repetitive at times (like Far Cry 2). Basically everything in dead worlds is hostile and out to kill ya. In a living world, NPC's interact, random events in the wild happen like traders fighting a gang or a bear happen, weather tends to come unpredictably, npc's roll on a schedule in towns or cities. So which do you prefer?