I want to create a game world in which a player and NPCs are able to do a couple of things: 1) move around 2) search and find things - harvesting, foraging etc 3) altering - building houses, planting etc In this world there will be "normal" outdoor areas which would do pretty well to be described by an array. However I also want there to be caves / towns and other special areas placed out in this world. The only approach I can think of is to use "array" based 2d maps to store location information - but that can get kind of big if it is a big world. Anyone know how games like Everquest or Ultima Online store their world data in memory? The question isnt only for graphical or other representational purposes but more for AI purposes - objects need to be able to "understand" the world easily. cheers, J