Choose any 50K+ World city, then continue naming 50K+ cities which are within 500 km of any previously named city. Please note – North/South America and the rest of the world are considered separate sections on this quiz. The game will not end if you haven’t begun one of them and then ‘jump’ over to it to begin working on it. So you get one free city to choose outside of the 500km distance if you want to start working on the section you haven’t started. But once you have started both NA/SA and Rest of World, you cannot guess a city outside a 500km circle or the quiz will end.