Liminal Roomgen is a drop-in performance engine for Liminal Industries and compatible forks — base LI, Rescripted, community remixes, anything using the standard KubeJS backrooms pipeline. Same rooms, same sector rules, dramatically better TPS. Minecraft 1.20.1 · Forge 47+ · KubeJS required.

Highlights

Fast placement — budgeted Java queue replaces per-tick script /place commands; no more exploration lag spikes
Reads your KubeJS sectors — picks from kubejs/config/sectors/ at runtime; change rooms in the pack and Roomgen follows
Rarity weighting — liminal corridors common, setpieces and loot rooms rare, with spacing so the maze feels intentional
Reliable expansion — graph grows when a room finishes, not on fragile per-node script loops
TPS HUD — /roomgen hud on or off for FPS / TPS / MSPT overlay
Dedicated server ready — runs server-side; clients sync live stats through the HUD

How it works

alt text KubeJS still owns room lists, sectors, and layout rules. Roomgen owns speed — picking, placing slices, and expanding connectors.

Pack layer (unchanged)

Sector JSON in kubejs/config/sectors/
Generation scripts (get_sector, get_random_room, room-node block ticks)

Roomgen layer (Java)

Bridge hooks your existing KubeJS handlers at startup
Native picker + classifier read the same sector files
Batch placer builds rooms within a per-tick time budget
Graph expander queues new nodes when a room completes

Remove the jar and generation falls back to vanilla KubeJS — fail-open, safe on existing worlds.

Room selection (overview)

alt text When a new grid node appears:

Dimension → overworld uses distance rings from center; poolrooms = sector 7; room forge = sector 8
Sector → load that sector's JSON pool (sectorN.json, plus #common_rooms / #community_rooms tokens)
Pick → weighted by rarity class when enabled, otherwise uniform random from the pool
Filter → spacing / dedup for rare classes; sector 6 uses the nest / sentinel triplet layout
Place → enqueue Java batch placement

Overworld sector rings (distance from -1000, -1000): outer rings pull sector 2 themed pools → void-adjacent sectors 3–6 with nest rings → inner sector 1 is common rooms only. Exact thresholds match the pack's step3.js and Roomgen's native picker.

KubeJS integration

Roomgen does not keep a separate room registry. It reads whatever your pack already has in kubejs/config/sectors/. Add or remove rooms in KubeJS — the mod picks them up on reload. No extra registration step.

Roomgen only writes room_classes.json (auto NBT scan for rarity tiers). Optional room_class_overrides.json for hand-tuned classes. Advanced packs can override the bridge at kubejs/roomgen_bridge.js.

Rarity classes

When enabled in config, rooms are weighted by class:

Liminal — plain wallpaper corridors (most common)
Standard — normal themed rooms
Large — big open layouts (uncommon)
Unique — rich setpieces (rare; once-per-dimension when enabled)
Loot — containers and spawners (rarest) Run /roomgen classify to rescan layouts, or classify full for a full rebuild.

Commands

/roomgen hud on / off — toggle performance overlay
/roomgen status — queue and health (ops / console)
/roomgen whereami — grid node, sector, room, and class
/roomgen findroom [type] — locate nearest special room (dev / testing)
/roomgen failures — recent placement errors
/roomgen rooms — placed-room counts by class (op)
/roomgen classify [full] — rescan room classes (op)

Config

config/liminal_roomgen-server.toml

[placement] — enable, expansion radius, graph expansion, spawn bootstrap
[performance] — tick budget, queue cap, relight deferral
[rarity] — class weights, dedup spacing, once-only rules for rare rooms
[debug] — verbose logging

For pack authors

Optional [rarity] knobs for modding and tuning (not needed for normal play): procedural vast rooms (vastRoomChance, extra vertical slices), class overrides in room_class_overrides.json, and custom pick hooks via kubejs/roomgen_bridge.js.

Compatibility

Works with Liminal Industries (base), Rescripted, and LI forks that keep the standard room-node + sector JSON setup. Rescripted is the primary dev target; the mod is not locked to one fork.

Needs KubeJS startup handlers (tick_layered_node, tick_spawn_node) and sector config under kubejs/config/sectors/. If a pack removes KubeJS generation entirely, Roomgen stays idle.

Requirements

Minecraft 1.20.1, Forge 47+
KubeJS 2001.6.5+
A Liminal Industries–style backrooms pack (base, Rescripted, or compatible fork)

More from this project

Part of an ongoing Liminal Industries tooling line. Liminal Relooted adds loot vignettes and void nest danger on the same pipeline. Check out my future work on CurseForge for more plug-and-play LI mods — drop the jar in, remove it cleanly, no manual script surgery. *