World

The Underworld

A cavern dimension under the Overworld bedrock, in grey fog that thickens over a 32-day cycle. A portal built on Overworld bedrock leads there; a portal anywhere else returns to the Overworld spawn. Adamantium is only found deep in the Underworld, above an unbreakable Mantle floor. Underworld dungeons hold Longdead spawners and loot.

The Underworld: a cavern dimension under the bedrock, grey fog

A portal built on Overworld bedrock	Stepping out into the Underworld	The exit portal in the Underworld
The fog thickens over a 32-day cycle	Fog at its densest, on the blood moon day	Underworld dungeon: Longdead spawner and loot chest
Bottom, stone removed: bedrock plate (back), Mantle floor (front)	Adamantium ore, deep in the Underworld (rock removed)	Nether floor cut open: the Core layer under the bedrock

Moons and weather

Full moons fall every 8 days. A blood moon comes every 32 days, announced by a harvest moon; a blue moon every 128 days, announced by a moon dog, stops hostile spawns under the open sky. The clock tells you tonight's moon. About one morning in eight brings thick fog.

A blood moon rising at dusk	Blood moon: frenzied undead roam the surface	Blue moon: no hostile spawns under the open sky
A normal full moon	Harvest moon, 8 days before a blood moon	Moon dog: heralds a blue moon 8 days later
Thick morning fog	The clock announces tonight's moon

Villages, runegates, ores

Villages only generate once someone has crafted an iron pickaxe, and they are abandoned, with dead crops. A runegate (a portal with a runestone on each corner) sends an empty-handed player far away. Silver, mithril and adamantium ores follow MITE's depth distribution.