The islands are not part of the main world. In fact, there really is no world map so to speak. Think about this: it isn’t a traditional world map. There is a large, and I mean large area between towns. But, after the towns are completed I or Savagebob have to go back and recreate the towns to be like 128x128 pixels. And they have to be animated. So, the world map is basically really a large area connecting the towns. To keep the lag down to a minimum I might put the world and the islands on a different map.

Edit: There is a world, as in a large chunk of world.