World spawn configuration · Kzeroko's Workshop

The spawn section decides where a new Overworld puts its spawn and how players arriving there are placed. Server operators and pack authors edit it; clients never read it. World spawn explains what the rules do in play.

Where the files live

Edit the spawn object in config/isekaiexpansion.json. It is a configuration file, not a data-pack format: there is one copy per server or single-player installation, and data packs cannot override it. In game, the same options appear under World Spawn (Server) in the mod’s config screen.

Minimal example

This fragment only switches the system on, which is already the default. Merge it into the existing file; every omitted option keeps its default.

{
  "spawn": {
    "enabled": true
  }
}

Fields

Distances are in blocks. Elevations are measured from sea level. Ranges are inclusive, and a value outside its range invalidates the whole section rather than being clamped.

Field	Type	Default	What it does
`spawn`	`object`	defaults below	Spawn selection and arrival settings. A missing or null object is restored to its defaults at load.
`spawn.enabled`	`boolean`	`true`	Chooses the world spawn by these rules and places arriving players on safe ground. `false` leaves both to vanilla.
`spawn.search`	`object`	defaults below	Where to look. See Search.
`spawn.ground`	`object`	defaults below	What ground is acceptable. See Ground.
`spawn.preferences`	`object`	defaults below	Biome and terrain weights. See Preferences.
`spawn.settlements`	`object`	defaults below	Villages to seek and structures to avoid. See Settlements.
`spawn.arrival`	`object`	defaults below	How arriving players are placed. See Arrival.

Search

Field	Type	Default	What it does
`spawn.search.centerX`	`integer`	`0`	Block X the search rings out from. Any integer.
`spawn.search.centerZ`	`integer`	`0`	Block Z the search rings out from. Any integer.
`spawn.search.radius`	`integer`	`3072`	Farthest distance from the centre at which a spawn may be chosen, `256–16384`.
`spawn.search.spacing`	`integer`	`48`	Distance between surveyed columns, `16–512`. Each column is shifted by up to `40%` of this so the grid does not show. Smaller values find more candidates and take longer.
`spawn.search.comfortRadius`	`integer`	`768`	Candidates within this distance of the centre keep their full score; one comfort radius further out, the score has halved. `0–16384`.
`spawn.search.chunkChecks`	`integer`	`12`	How many of the best candidates may be generated and searched for a safe block, `1–64`. The shortlist holds `32` candidates or twice this number, whichever is larger.

Ground

Field	Type	Default	What it does
`spawn.ground.minElevation`	`integer`	`2`	Lowest acceptable ground above sea level, `1–128`.
`spawn.ground.maxElevation`	`integer`	`64`	Highest acceptable ground above sea level, from `minElevation` to `256`. Ground more than `40` blocks up scores up to `40%` lower.
`spawn.ground.maxRelief`	`integer`	`9`	Largest height difference allowed across `8` samples `10` blocks from the candidate, `1–64`.
`spawn.ground.shoreClearance`	`integer`	`32`	Outer radius of `16` water samples that lower the score, ocean counting twice, `0–256`. `0` skips them. Water at the fixed samples `10` and `24` blocks out always rejects the candidate, whatever this value.
`spawn.ground.landmassRadius`	`integer`	`96`	Radius of the inner of two rings of `16` land samples; the outer ring is twice as far. `16–512`.
`spawn.ground.landmassShare`	`number`	`0.85`	Share of those `32` samples that must be dry land, `0–1`. Rejects islets and narrow spits.

Preferences

Both lists hold rules written as id=weight. Rules are tried in order and the first one that matches wins. A weight of 0 forbids the match, 1 is neutral and 4 is the maximum.

Field	Type	Default	What it does
`spawn.preferences.unlistedBiomeWeight`	`number`	`0.45`	Weight of a biome no biome rule matches, `0–4`.
`spawn.preferences.biomeWeights`	`array<string>`	36 rules	Biome rules. Each is a biome ID or a `#tag` followed by `=weight`, such as `#minecraft:is_ocean=0` or `minecraft:plains=1`. An empty list gives every biome the unlisted weight.
`spawn.preferences.terrainWeights`	`array<string>`	20 rules	Terrain family rules, such as `isekaiexpansion:great_plains=1.2`. Tags are not accepted. A family with no rule, and ground outside any family, weighs `1`.

The default biome rules forbid #minecraft:is_ocean, #minecraft:is_river, minecraft:mushroom_fields, minecraft:deep_dark, minecraft:frozen_peaks, minecraft:jagged_peaks and minecraft:stony_peaks, and weigh isekaiexpansion:great_plains at 1.2. The default terrain rules forbid isekaiexpansion:world_tree, isekaiexpansion:halo_crown, isekaiexpansion:sentinel_isles, isekaiexpansion:verdant_knives and every exotic family, weigh isekaiexpansion:luminous_grove and isekaiexpansion:starlit_glade at 0.6 and isekaiexpansion:amber_basin at 0.3. Open the generated file to see every default rule.

Settlements

Structure selectors are structure IDs or #tags, such as #minecraft:village or minecraft:pillager_outpost.

Field	Type	Default	What it does
`spawn.settlements.bonus`	`number`	`0.35`	Score raise for a forecast settlement at the preferred distance, `0–4`. `0.35` raises a candidate by up to `35%`; `0` turns the settlement pass off.
`spawn.settlements.minDistance`	`integer`	`64`	Closer settlements give partial credit, down to half at the candidate itself. `0–4096`.
`spawn.settlements.maxDistance`	`integer`	`512`	Settlements up to this far give full credit; credit fades to none at twice this distance. From `minDistance` (at least `1`) to `4096`.
`spawn.settlements.structures`	`array<string>`	`["#minecraft:village"]`	Structures that count as settlements. An empty list turns the settlement pass off.
`spawn.settlements.avoidStructures`	`array<string>`	18 structures	Structures a spawn keeps away from: ancient cities and pillager, illager, witch, dragon and boss structures from vanilla and the pack’s mods. A candidate with one forecast in range keeps `10%` of its score. An empty list turns the check off.
`spawn.settlements.avoidRadius`	`integer`	`160`	How far a hostile structure reaches, `0–1024`. `0` turns the check off.

Arrival

Field	Type	Default	What it does
`spawn.arrival.safeArrival`	`boolean`	`true`	Places a player joining for the first time, or respawning without a respawn point, on a safe block inside the `spawnRadius` game rule instead of vanilla’s scatter.
`spawn.arrival.searchRadius`	`integer`	`24`	When the spawn radius has no safe block, how far around the world spawn to search, `0–64`.

Validation

The server checks the whole section each time a search runs. One bad value makes the section invalid; nothing is clamped or skipped.

Out-of-range number, malformed rule or invalid ID. At world creation, the server logs an error naming the option and uses vanilla spawn selection. /ise spawn survey and /ise spawn relocate print the same message and change nothing.
Weight rules. A rule needs an = with text on both sides. The key is lowercased; the weight must be a number in 0–4. A #tag in terrainWeights is an error. A well-formed ID that names no biome, tag or family is accepted and never matches.
Structure selectors. Only the syntax is checked in the config. An ID or tag that names nothing is skipped with a warning in the log when a search runs.
Duplicate rules. The first matching rule wins; later duplicates are ignored.
Missing keys and null sections. A missing key takes its default. A null section is restored to its defaults when the file loads. A null list is an error.
Unknown keys. Ignored. A misspelt option is silently left at its default.

spawn.arrival is read without the full check: arrival placement uses enabled, safeArrival and searchRadius, clamping the last to 0–64, so it keeps working while another option is invalid.

Reloading

The file is read when the game starts. Every search and every player arrival reads the loaded settings afresh; nothing is cached between searches. The settings are server-local and never sent to clients.

Changing the settings does not move an existing world’s spawn. The world spawn is chosen once, when the world is created; to apply new settings to an existing world, run /ise spawn relocate.

World spawn — how the rules pick a spawn, and the two commands.
Terrain configuration — the terrain families these weights refer to.
Terrain and landmarks — what each family looks like.