NetherExpanse by CevAPI

NetherExpanse removes the Nether roof, keeps normal terrain below Y 256, and raises the Nether dimension height so optional sky content can exist above the normal terrain ceiling. Most screenshots are of the Incendium compatible version.

Packaging note:

NetherExpanse is now distributed as four separate standalone datapacks.
This split exists to satisfy Modrinth's packaging requirements and to make installation clearer.
Each variant is self-contained. Do not stack multiple NetherExpanse variants together.
Pick exactly one NetherExpanse datapack for a world.

Available standalone variants:

This One

Vanilla-compatible standalone datapack with all NetherExpanse structures enabled.

NetherExpanse Incendium

Standalone datapack with all NetherExpanse structures enabled and built-in Incendium compatibility.

Nether Expanse (No Structures) [Link Updated When Approved]

Vanilla-compatible standalone datapack with NetherExpanse terrain changes enabled but all NetherExpanse structures disabled.

NetherExpanse Incendium (No Structures) [Link Updated When Approved]

Standalone datapack with NetherExpanse terrain changes, all NetherExpanse structures disabled, and built-in Incendium compatibility.

Which one should I use?

Not using Incendium: choose one of the non-compat variants.
Using Incendium: choose one of the IncendiumCompat variants.
Want sky structures, Nether cities, and Nether ancient cities: choose an AllStructures variant.
Want only the terrain/dimension changes without NetherExpanse structures: choose a NoStructures variant.

Shared settings:

Terrain top: tapers out by Y 256
Dimension height: 416
The terrain cap can be adjusted in data/minecraft/worldgen/noise_settings/nether.json before creating a world.
Keep noise.height and the dimension height above the terrain cap so terrain tapers into open sky instead of flattening.
The noise override includes preliminary_surface_level so newer 1.21.x and 26.1.x loaders accept the registry entry.

Structures included in the `AllStructures` variants:

nether_expanse:sky_spawn_portal Rare bedrock sky portal hypercube at Y 280. Purple portal particles appear in the center; entering that center effect teleports you to a safe Nether location within 1000 blocks of 0,0, below Y 128.
nether_expanse:nether_city Very rare Nether city generated from the bundled templates, surface-anchored with red and black shulkers and high-end Nether loot.
nether_expanse:sky_nether_ship Extremely rare flying ship at about Y 322, generated from the bundled template, with super-rare premium loot.
nether_expanse:nether_ancient_city Nether ancient city generated at low Y with custom hostile spawns and high-end Nether loot.

Structure rarity in the `AllStructures` variants:

Spawn portals: spacing=160, separation=64
Nether cities: spacing=224, separation=96
Nether ancient cities: spacing=224, separation=96
Nether ships: spacing=384, separation=160

Nether ancient city rarity vs other structures:

Candidate density is roughly proportional to spacing^2 before biome checks.
Nether ancient city (spacing=224) is about 50176 / 25600 ~= 2.0x rarer than spawn portals (spacing=160).
Nether ancient city (spacing=224) is the same rarity as Nether cities (spacing=224).
Nether ancient city (spacing=224) is less rare than Nether ships (spacing=384).
Nether ancient city (spacing=224) is about 50176 / 729 ~= 69x rarer than vanilla bastion candidates (spacing=27).

Rarity reference vs vanilla bastions:

Vanilla bastion remnants use spacing=27, about 1 candidate per 27x27 = 729 chunks before biome checks.
NetherExpanse spawn portals (spacing=160) are about 25600 / 729 ~= 35x rarer than bastion candidates.
NetherExpanse Nether cities (spacing=224) are about 50176 / 729 ~= 69x rarer than bastion candidates.
NetherExpanse Nether ancient cities (spacing=224) are about 50176 / 729 ~= 69x rarer than bastion candidates.
NetherExpanse Nether ships (spacing=384) are about 147456 / 729 ~= 202x rarer than bastion candidates.

Useful commands for the `AllStructures` variants:

/execute in minecraft:the_nether run locate structure nether_expanse:sky_spawn_portal
/execute in minecraft:the_nether run locate structure nether_expanse:nether_city
/execute in minecraft:the_nether run locate structure nether_expanse:sky_nether_ship
/execute in minecraft:the_nether run locate structure nether_expanse:nether_ancient_city

Known issues:

This does not behave well with ViaFabric due to lighting changes in 26.1.x, so if a server on 1.21.11 has this datapack and a 26.1.2 client joins it, shadows will be pitch black. Users must connect to the server using the same-version client as the server.