Sky island. It's the best one I've found. There are several islands in the sky, with quests to complete. You spawn on the biggest one, but there is a bigger one in the works. There are other island, such as one with a quest, and one which is upside down. All island are amazingly terraformed, including underground. The creator, Genorator, has been working on an update. There are also bullseye things you are supposed to find. There is also an included story mode, but I won't tell you the end. Please note, there are other worlds with similar names, none of them are half as good; get Generator's.