Custom Biome Definition

Defines one custom biome. It is registered as soon as the page is saved, and written to a generated datapack so it survives a restart.

Every field left empty is inherited: first from the preset if one is set, then from the base biome. Only what you fill in is overridden.

Identification

Field	Type	Description
biomeId	String	Biome id, lowercase with underscores (e.g. corrupted_forest)
namespace	String	Namespace for the key, typewriter by default

The final key is namespace:biomeId, for example typewriter:corrupted_forest. That is what you pass to actions, events and commands.

Inheritance

Field	Type	Description
baseBiome	String	Vanilla biome to inherit from (e.g. minecraft:dark_forest)
preset	Ref	Optional preset providing shared colours and attributes

The base biome supplies everything you do not override, including mob spawns, features and carvers. Choosing a base close to the mood you want is the least work: a frozen biome should start from minecraft:snowy_taiga, not from plains.

Climate

Field	Type	Description
temperature	String	0.0 cold, 0.5 temperate, 2.0 hot. Empty inherits.
downfall	String	0.0 dry to 1.0 wet. Empty inherits.

Temperature drives snow and rain, not just colour: below 0.15 precipitation falls as snow.

Colours

Hex format #RRGGBB. Empty inherits.

Field	Description
fogColor	Fog
skyColor	Sky
waterColor	Water
waterFogColor	Underwater fog
grassColor	Grass
foliageColor	Leaves
dryFoliageColor	Dry foliage, badlands and savanna
sunriseSunsetColor	Sunrise and sunset tint
cloudColor	Clouds
skyLightColor	Skylight tint

Visual attributes

All optional. Leave empty to inherit.

Field	Type	Description
fogStartDistance	Float	Where fog begins
fogEndDistance	Float	Where fog is full
skyFogEndDistance	Float	Where sky fog ends
waterFogStartDistance	Float	Where underwater fog begins
waterFogEndDistance	Float	Where underwater fog ends
cloudFogEndDistance	Float	Where cloud fog ends
cloudHeight	Float	Cloud altitude
skyLightFactor	Float	Skylight brightness, between 0.0 and 1.0
sunAngle	Float	Sun angle, 0.0 overhead
moonAngle	Float	Moon angle
starAngle	Float	Star angle
starBrightness	Float	Star brightness
moonPhase	String	full_moon, waning_gibbous, …

[!WARNING] Values outside the range the server accepts cause the biome to be rejected at registration, with the offending value named in the console. The other biomes keep working.

Example

A corrupted forest built on dark forest, taking its night atmosphere from a preset:

biomeId:      corrupted_forest
namespace:    typewriter
baseBiome:    minecraft:dark_forest
preset:       nuit_spectrale
temperature:  0.7
downfall:     0.8
grassColor:   #4A5D23
foliageColor: #3D4F1C
waterColor:   #2E4034

Sky, fog and stars come from the preset, so a sister biome sharing the same night can reuse it without repeating a single value.

Checking the result

/tw biome list shows every definition and whether it is live in the registry or waiting for a restart. /tw biome info reports the biome under a player.