Sky Island is a cube game where the world is mostly empty at first except for a small floating island on a sea.
You start out standing on the island. Your rank is Level 1. There are 10 quests to complete. When a quest is achieved, you get a reward. When all 10 quests are achieved, you are promoted to Level 2 and given new quests with new rewards.
Finish the Level 2 quests, and there is a Level 3. Finish Level 3 and you graduate as a Sky Island Master. You are granted Fly and Fast privileges and may build what you wish.