WorldEngine

A performance-oriented multi-world management mod for Fabric servers. Run as many worlds as you need — with per-world rules, isolated inventories, and custom portals — without tanking your TPS.

Minecraft: 1.21.11 | Loader: Fabric | Required: Fabric API ≥ 0.141.0

Features

Multi-World Management

Create and manage worlds at runtime — no server restarts required. Supports 9 generator types: overworld, amplified, large_biomes, nether, end, void, flat, caves, and floating_islands. Worlds are loaded on demand and persist across restarts.

Per-World Rules

Each world can have its own:

• Gamemode — enforce survival, creative, adventure, or spectator per-world
• PvP — enable or disable player combat independently of other worlds
• Difficulty — peaceful through hard, per world
• Gamerules — override any vanilla gamerule (keepInventory, mobGriefing, etc.) per world

Inventory Isolation

Group worlds together to share inventories, or keep them fully separate. Items, armor, hotbar, ender chest, hunger, XP, and status effects are all saved and restored on world transition. Worlds not in any group use independent inventories.

Mob Spawn Control

Block or allow mob spawning at the category level (monsters, creatures, ambient, etc.) or target specific entity types. Rules stack: entity-specific rules take priority over group rules.

Custom Portals

Build portal frames from ore blocks — iron, copper, redstone, lapis, diamond, gold, emerald, or netherite (any size, min 4×5 interior). The entire frame must be one block type. Link portals to any world, then activate by right-clicking the frame with the matching ore item. Portals use a custom animated block that won't interfere with vanilla nether or end portals. Stepping into an active portal starts a 1.5-second warmup countdown — step out to cancel. Portals can be one-way or bidirectional, and links survive server restarts.

Performance

• Worlds unload automatically after a configurable idle timeout
• Worlds with no players skip tick processing entirely
• Saves are staggered to avoid simultaneous disk I/O spikes
• Worlds are only loaded when a player actually enters them

Installation

1. Install Fabric Loader for Minecraft 1.21.11
2. Install Fabric API ≥ 0.141.0
3. Drop worldengine-1.3.0.jar into your mods/ folder — on both server and client
4. Start the server — config files are created automatically in config/worldengine/

Note: Fantasy is bundled inside the JAR. You do not need to install it separately.

Client mod required for portals. The mod must be installed client-side to see and use custom portal blocks. Without it, portals are non-functional but the server won't crash. All other features (world management, rules, inventories, mob control) are server-side only.

Commands

All commands require operator level 2 (Gamemaster) unless noted.

World Management

Per-World Rules

Inventory Groups

Mob Spawning

Spawn group names: monster, creature, ambient, axolotls, water_creature, water_ambient, underground_water_creature, misc

Portals

Portal Setup

Client mod required for portals.

1. Build a frame from ore blocks — iron, copper, redstone, lapis, diamond, gold, emerald, or netherite blocks (at least 4×5 interior, any larger size works). The entire frame must be one type.
2. Right-click the frame with an empty hand (OP only) to select it
3. Run /we portal link <world> to link it one-way, or /we portal link <portalname> to link two named portals bidirectionally
4. Activate by right-clicking the frame with the matching ore item (e.g., diamond for a diamond block frame) — consumes 1 item in survival
5. Walk into the portal — a 1.5-second countdown appears on the action bar, then you teleport. Step out to cancel.

To create a two-way portal: build frames in both worlds, name each with /we portal name <name>, then run /we portal link <other-portal-name> from each side. Activate both sides with the matching ore item.

Breaking a frame block deactivates the portal. Repair the frame and re-activate with another ore item.

Configuration

Config files are stored in config/worldengine/ on your server:

• config.json — global defaults and performance settings (idle timeout, save interval, etc.)
• worlds/<name>.json — per-world settings (auto-created when a world is made)
• inventory-groups.json — inventory group assignments
• portals.json — portal link data

All config is hot-written on change — no server restart required after running /we commands.

Compatibility

• Works alongside vanilla dimensions (overworld, nether, end) — custom portals do not interfere with nether or end portals
• Compatible with LuckPerms (suggested, not required)
• Server-side for all features except portals — portal blocks require the mod on both server and client