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Spreadrooms

The backrooms spread throughout your world.

Fabric
Loaders
Fabric
Downloads on Modrinth
98
Followers on Modrinth
1
versions
2
Updated
August 20, 2026Aug 20
Published
in 2026
Room Example — Singular room in the spreadrooms! · swipe

At a glance

Runs on Fabric
For Minecraft 26.2
Server only — players don't need to install it
Latest version — v0.2-alpha from August 20, 2026
License CC0-1.0 — free
Where it's needed
In gamenot neededOn serverrequired

Install on the server only; players don't need it

Game versions26.2

They are spreading...

⚠️ DO NOT USE THIS MOD IN A WORLD YOU CARE ABOUT!!! IT WILL DESTROY BLOCKS AUTOMATICALLY!!

This mod adds the 'backrooms' into vanilla minecraft that will slowly spread and consume your world!
This mod is only required to be on the SERVER since it doesnt add any new blocks, items, etc.

The mod is very customizable and allows you to change everything about how to rooms spread and what blocks they use.

Information

Currently, the mod creates a worldborder of size 200 (configurable) centered on the player that runs the
/spreadrooms start command. You CANNOT turn this off yet!
The spreading of the rooms can get VERY laggy if you dont configure it right, also, it may be a good idea to let it generate for a bit before you start playing since it can be slow.

Commands

/spreadrooms start
⮡ starts the spread
/spreadrooms stop
⮡ stops the spread
/spreadrooms reset
⮡ removes all rooms from memory and resets the worldboard to vanilla
/spreadrooms reload
⮡ reloads the config
/spreadrooms debug rooms_count
⮡ lists how much of each room type exists
/spreadrooms debug rooms_ticking
⮡ returns list of all active rooms

Configuration

located at /config/spreadrooms.json

areaFromCenter: 100
⮡ Worldborder size and spreadrooms origin, starts in southeast corner
timeToSpread : 20
⮡ Ticks inbetween spread
timeToSpreadVariation : 0
⮡ Random variation +/- for timeToSpread, disabled with 0
timedSpread : true
⮡ ⚠️ HEAVY PERFORMANCE IMPACT IF FALSE! Toggles between spreading every tick and using timeToSpread and timeToSpreadVariation
strictGeneration : true
⮡ May impact performance! When true forces rooms to set blocks to air.
generateOnPlane : true
⮡ Attempts to get rooms on a similar y-level
connectRooms : true
⮡ Rooms next to eachother will remove touching walls when generating
maxGenRooms : 5
⮡ ⚠️ PERFORMANCE IMPACT! Numbers of rooms generating at once
defaultRoomSize : Size of [ x : 6, y : 4, z : 6]
⮡ Values x, y, and z define the default room size
sizeVariation : Size of [ x : 7, y : 1, z : 7]
⮡ Gets a random number between 0 and the value
sizeVariationShift : Size of [ x : 1, y : 0, z : 1]
⮡ Subtracts from the randomized sizeVariation number
sizeVariationFactor : Size of [ x : 2, y : 2, z : 2]
⮡ Multiplies by the sizeVariationShift number and adds to the respective value of the rooms size
roomBlocking : true
⮡ ⚠️ PERFORMANCE IMPACT! Cuts bigger rooms into smaller ones to make big room generation faster
maxRoomSize : Size of [ x : 8, y : 6, z : 8]
⮡ Rooms bigger than any of these axis will but cut if roomBlocking is true
featureStates : Map of [ RoomFeature, BlockID ]
⮡ Allows users to define what most of the features look like
⮡ The features GREEN, CARPET, E_PIPES, and E_CHAINS cant be changed

How it works

Creates a new record object called a 'room' with origin, size, and room features properties. Rooms have a method called search which checks if adjacent blocks are already set to the correct block, and if not it sets the block. It repeats this recursivley until the room is completed. Additionally, if a search returns a position outside the room, it generates a new set of random room properties, checks if that room will fit if places in the position, and if so, places the room. New rooms are added to the queue to be ticked, since only a maximum amount of rooms can be ticked at once. When where a block is placed, a room checks its room features and neighbors. This allows different rooms to connects, and room features allow a large variation of rooms. Room features are easily customizable and editable, and allow for unique walls, floors, patterns, structures, and other things to appear in rooms. Thats basically it so far! if your still curious, you can check out the github repo for youself!

Whats planned

  • Ability to have simple user created features like custom floors, walls, etc
  • Many more "RoomFeatures" to add variation to the rooms, and a reason for entering

FAQ

How to install Spreadrooms?

Install Fabric for your Minecraft version, download Spreadrooms for the same version and loader, put the file into the mods folder and launch the game with the loader profile.

Which Minecraft versions does Spreadrooms support?

Spreadrooms has builds for Minecraft 26.2.

Is Spreadrooms needed on the server?

Server only — players don't need to install it

License and source
Creative Commons Zero v1.0 Universalfree to use and share with credit to the author
Original — Modrinth↗Files unchanged, verified with SHA-512Is this your mod? For rights holders

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