Custom

Customized is a world type that replaces the normal varied terrain of the Overworld with custom features. It can be edited via JSON files.

Access
Custom world generation works using JSON files, which need to be imported before world creation.

In the world creation menu, go to more options and select the "Import World" option. Then, select a world generation JSON file. A screen will pop up, warning users that custom worlds are experimental. Click "Yes" to continue.

The only way to access added dimensions is through commands, such as, which will teleport the player to the specified dimension (see ).

JSON format
Custom generation files take the following format:


 * The root tag.
 * Can be true or false. Whether the world has a bonus chest or not (equivalent to bonus chest option).
 * : Can be true or false. Whether structures should be generated or not (equivalent to generate structures option).
 * : The numerical seed of the world.
 * : A list of the dimensions in this world where the key is the namespace id of the dimension. The dimensions minecraft:overworld, minecraft:the_nether and minecraft:the_end are required for a well functioning world. Any other namespaced ID is allowed for custom dimensions.
 * This can be a list of options for the dimensions OR the namespace id of one of the default dimensions as a string, the dimensions will the use the settings of the specified dimension.
 * Can be true or false. Whether the dimensions behaves like the nether (water evaporates and sponges dry) or not.
 * : Can be true or false.
 * : Can be true or false. Determines whether the dimension is treated as eight meters per block like in the Nether.
 * : Can be true or false. Whether the dimension has skylight access or not.
 * : Can be true or false. Whether the dimension has a bedrock ceiling or not.
 * : How much light the dimension has, default is 0.5 in the demo file (for upper and lower bounds as well as precise effect).
 * : Can be false or any integer from 0 to 24000. If this is set to a number, the time of the day will always be the specified value.
 * Generation settings used for that dimension.
 * The ID of the generator.
 * .: The seed used to generate the dimension. In most cases, this is exactly the same as the world seed, but can be different and the dimension generated will be based upon this seed and not the world seed.
 * The shape of the terrain. Can be a string to use a preset, valid values are minecraft:overworld, minecraft:nether, or minecraft:end (potentially incomplete list) or a compound with a list of options
 * The y coordinate of the bedrock roof, if out of bounds (0-255) the roof will not appear
 * The y coordinate of the bedrock floor, similar to bedrock_roof_position
 * The sea level in this dimension between 0 and 255
 * Can be true or false.
 * Structure settings
 * List of structures to use in this dimension
 * The key for this field should be the namespaced id of a structure, a list is available here (page needs updating) (all possible values are not required, omitting one will cause it tonot appear in this dimension )
 * Spacing between structures, unit? (probably chunks), min, max or average?
 * (number)
 * (number)
 * : Parameters for world generation
 * : (number)
 * (number)
 * (number)
 * : (number)
 * (number)
 * (number)
 * : (float)
 * (float)
 * (float)
 * (float)
 * (float)
 * (float)
 * (float)

Some possible values for and associated extra contents are:


 * noise – Default generator settings. Used in minecraft:overworld, minecraft:the_nether and minecraft:the_end with the "World Type" option when creating a new world set to "Default".
 * The seed used to generate the dimension. In most cases, this is exactly the same as the world seed, but can be different and the dimension generated will be based upon this seed and not the world seed.
 * The shape of the terrain. Can be minecraft:overworld, minecraft:nether, or minecraft:end (potentially incomplete list).
 * Settings dictating which biomes and biome shapes.
 * The seed used for biome generation. In most cases, this is exactly the same as the dimension seed (and by extension the world seed), but can be different and the biome generation for this dimension will be based upon this seed and not the dimension seed.
 * The type of biome generation. Arguments lie in the biome_source compound.
 * vanilla_layered Biome generation used in the overworld.
 * Whether the biomes are large. True for the biomes in the "Large" world type.
 * multi_noise 3D biome generation used in the nether.
 * The set of biomes to be used.
 * the_end biome generation used in the end with biome minecraft:the_end in the center and other end biomes around.
 * fixed a single biome.
 * The single biome to generate.
 * checkerboard a biome generation where biomes are square (or close to square) and repeat along the diagonals.
 * A list of biomes that repeat along the diagonals (can be more than 3).
 * Determines the size if the squares on an exponential scale.
 * vanilla_layered