Note: I came up with most of these ideas (except volcanos) on the Minecraft Wiki on Gamepedia.
Volcanos added. Volcanos erupt every 60-65 ticks.
New dimension: Negative Dimension. Everything is photo negative-ish, the world (and coordinates) are reversed, passive mobs are hostile and vice-versa. To get there, you need to build a portal (like the Nether Portal) out of coal blocks and then put water on it.
Nether villages added. They are like regular villages in the overworld, but the houses are made of nether bricks and nether stone (see below) and the wheat farm is replaced with a nether wart farm. There are Nether villagers and they have the same professions as their overworld counterparts do.
There is a 1/50 chance that an ore will spawn in …
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