Since the turn of the millennium, 'open world' has become one of the biggest buzzwords in gaming. Whenever something gets announced that promises players the freedom to explore a whole city, continent or world, our ears instantly prick up with anticipation. Open-world titles offer a unique kind of escapism that just can't be replicated by equally competent, yet linear releases, and whilst bigger doesn't always mean better, we still instinctively attribute a lot of value to it. Despite the genre having been around for a while, there's still something magical about being able to say, "I'm just going to go in a straight line in that direction and see what I find", and whether said world is packed with quests, towns and random people to rob and murder, or is just a sprawling empty wasteland with nothing but beautiful scenery, the allure of the open world is always there. As a way of celebrating the expanse of open worlds, here are the ten of the biggest in gaming so far, ranked in order of size in square miles (MMOs not included).