The Underground World is the fourth level in Craft the World. The difficulty is set to hard in campaign. It consists mostly of earth and stone blocks, along with some sand. The weather type is rain, which provides water and lakes on the surface. A new rock called sulfur can be used to make gunpowder for guns and ammo. The underground is very deep.
The Underground World features new animals and monsters.
Caterpillar (equivalent of the Sheep / Llama)
Cave Beast (equivalent of the Wild Boar / Bull / Ice Boar)
Flying Octopus (equivalent to the Hen / Ice Bird / Blue Bird for drops, but also flies and attacks)
Small Caterpillar (equivalent of the Slug)
Technologies and Items
The Underground World also features completely new technologies, each of them with its items.
Some items were added to already existing technologies:
Steel Ladder to Expert Construction
Mushroom Pies to Advanced Cooking
Steel Wall to Master Construction (replacing the Brick Wall, which was moved to Advanced Fortifications)
Rifle and Steel Ammo to Expert Weaponry