Java Edition 21w40a

21w40a is the fourth snapshot for Java Edition 1.18, released on October 7, 2021, merged and renamed some biomes, tweaked world generation and mob spawning.

Biomes

 * The unused height variation sub-biomes have been removed from the code and merged with their default biome variants, as following:
 * {| class="wikitable collapsible collapsed"

! Name
 * Badlands Plateau
 * Bamboo Jungle Hills
 * Birch Forest Hills
 * Dark Forest Mountains
 * Desert Hills
 * Desert Lakes
 * Giant Spruce Taiga Hills
 * Giant Tree Taiga Hills
 * Jungle Hills
 * Modified Badlands Plateau
 * Modified Gravelly Mountains
 * Modified Jungle
 * Modified Jungle Edge
 * Modified Wooded Badlands Plateau
 * Mountain Edge
 * Mushroom Field Shore
 * Shattered Savanna Plateau
 * Snowy Mountains
 * Snowy Taiga Hills
 * Swamp Hills
 * Taiga Hills
 * Taiga Mountain
 * Tall Birch Hills
 * Wooded Hills
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * Modified Wooded Badlands Plateau
 * Mountain Edge
 * Mushroom Field Shore
 * Shattered Savanna Plateau
 * Snowy Mountains
 * Snowy Taiga Hills
 * Swamp Hills
 * Taiga Hills
 * Taiga Mountain
 * Tall Birch Hills
 * Wooded Hills
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * Taiga Hills
 * Taiga Mountain
 * Tall Birch Hills
 * Wooded Hills
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"
 * }
 * Some biomes have been renamed:
 * {| class="wikitable collapsible collapsed"

! Old name !! New name
 * || Windswept Hills
 * || Old Growth Spruce Taiga
 * || Old Growth Pine Taiga
 * || Windswept Gravelly Hills
 * || Sparse Jungle
 * || Jagged Peaks
 * || Windswept Savanna
 * || Frozen Peaks
 * || Snowy Plains
 * || Stony Shore
 * || Old Growth Birch Forest
 * || Wooded Badlands
 * || Windswept Forest
 * }
 * Non-cave biomes (e.g. Savannas) no longer change with height.
 * Tweaked the relative size of some biomes, to match 1.17 a bit closer.
 * Increased the average size of most biomes.
 * || Snowy Plains
 * || Stony Shore
 * || Old Growth Birch Forest
 * || Wooded Badlands
 * || Windswept Forest
 * }
 * Non-cave biomes (e.g. Savannas) no longer change with height.
 * Tweaked the relative size of some biomes, to match 1.17 a bit closer.
 * Increased the average size of most biomes.
 * }
 * Non-cave biomes (e.g. Savannas) no longer change with height.
 * Tweaked the relative size of some biomes, to match 1.17 a bit closer.
 * Increased the average size of most biomes.

Blocks

 * Copper Ore
 * Now drop 2-5 Raw Copper when mining instead of 2-3.


 * Stonecutter
 * Block of Copper can be converted to 4 Cut Copper using stonecutter.

Mobs

 * Axolotls
 * Now only spawn in water above clay blocks in lush caves.


 * Cod, Salmon, Pufferfish, Tropical Fish, Squid, and Dolphins
 * Now only spawn in water from Y=50 to Y=64.
 * Additionally, tropical fishes now also spawn in lush caves at any height.


 * Glow Squids
 * Now only spawn in water blocks under Y=30.


 * Goats
 * No longer spawn in Stony Peaks.


 * Zombies
 * Now also spawn in Dripstone Caves again.

World generation

 * Ore distribution
 * Copper Ore now generates between Y=-16 and Y=112, generating the most at Y=48, and increased the number of blobs.
 * This allows deepslate copper ore to generate again.
 * Added more unexposed Diamonds.
 * Decreased minimum generation height of Emerald Ore from Y=32 to Y=-16, and increased the number of blobs.
 * This allows deepslate emerald ore to generate again.
 * Extra gold generates below Y=-48.
 * Decreased minimum generation height of the upper range of Iron Ore from Y=112 to Y=80, and increased the number of blobs.


 * Dungeons
 * Increased the amount of dungeons, especially below Y=0.


 * Gravel
 * Now generates below Y=0, and increased the number of blobs.


 * Lakes
 * Water lakes were removed, because Aquifers could provide local water levels.


 * Magma Blocks
 * Slightly increased the frequency of underwater magma.


 * Villages
 * Now slightly more spread out.


 * General
 * Bedrock layers generate dependent on the world seed now.

Gameplay

 * Advancements
 * Reduced the number of biomes required to visit for the "Adventuring Time" advancement from 42 to 31, due to the removal of sub-biomes.

General

 * AI
 * Optimized AI for Axolotls, Goats, Hoglins, Zoglins, Piglins, Piglin Brutes and Villagers.

Video
Videos made by slicedlime: