1) Think of States as being like chapters in a book. You'd work your way through one entirely, and when finished, move on to the next (i.e. Loader, MainMenu,, Level Select, Game, Game Over). I wouldn't use a State for a mini-map, that is an in-game element. 2) World is exactly as you say, just a container sat on the Stage. You can place elements above it (on the Stage, above the World group), for example UI. But otherwise that's it, World is just a Group in which