At the start of play, place the Sky Islands game board so that it shows either two or three islands in the sky (your choice), then use the Small World game board as if you were playing with one fewer player, i.e., use the four-player board when playing with five players. Next, place access points to the Sky Islands - the beanstalk and the stairway - on different regions on the game board. Whenever a race stands on one of these access points, they can try to conquer the space on the sky islands that shows the matching symbol.
Races can't start their conquests in the Sky Islands unless their power specifically allows them to do so. At the end of a turn, if you control all of the regions on a Sky Island, you gain one additional coin.
