They Are Legion

They Are Legion adds persistent zombie hordes to Minecraft.
Instead of spawning huge numbers of entities all the time, the mod simulates hordes as lightweight server-side populations, then materializes real vanilla zombies only when they become relevant near players.

The goal is to create the feeling of a living undead threat moving through the world: hordes can migrate, grow over time, react to player activity, and eventually pressure or siege a base when enough heat and noise is generated.

❤️ Support

If you enjoy this mod and want to support its development and future updates, you can do so here: https://ko-fi.com/markusotto

Features

Persistent zombie hordes saved per dimension.
Natural horde spawning around players.
Hordes migrate through the world instead of appearing only as instant events.
Horde populations grow as Minecraft days pass.
Configurable evolution modes:
- Easy
- Medium
- Hard
- They Are Legion
Heat and noise system that can attract or alert nearby hordes.
Player actions such as mining, fighting zombies, building activity, base presence, and compatible gunfire events can increase danger.
Automatic escalation from wandering hordes to pressure or siege behavior.
Progressive materialization into vanilla zombies near players.
Configurable limits for physical zombies per horde and per dimension.
Forge config screen for tuning the main settings.
Admin/debug commands for testing hordes, heat, noise, and performance.

Recommended Pairing

They Are Legion was originally created to pair well with my other mod, Turret TaCZ Addon.

The idea was simple: if players can build fortified bases with automated turrets and firearms, the world needs a threat large enough to make those defenses matter. Roaming hordes, heat, noise, and siege pressure are meant to create that kind of survival-defense loop.

Turret TaCZ Addon is not required to use They Are Legion. The mod can also work well with other infection, zombie, combat, weapon, or survival overhaul mods.

Performance Approach

They Are Legion does not keep every zombie in a horde loaded as a real entity at all times.

Most of the time, a horde exists as an abstract population with a position, behavior, target, and movement state. When a horde gets close enough to matter, the mod gradually spawns controlled groups of vanilla zombies to represent it physically.

This helps keep the feeling of large hordes while avoiding thousands of ticking entities.

Heat, Noise, and Sieges

Player activity can leave signals in the world.
A quiet player may simply see hordes pass through the region, while a noisy or heavily developed base can become a target.

A horde can react to:

Mining and block breaking
Zombie kills
Base activity
Bed/base pressure
Noise commands for testing
Optional compatible gunfire events

When enough pressure builds up, nearby hordes can become more aggressive and may attempt to move toward the source.

Compatibility

Physical horde zombies are vanilla zombies with persistent horde data.
This helps preserve compatibility with resource packs and many mods that modify vanilla zombie visuals or behavior.

Mods that fully replace zombie AI, replace the zombie entity, or heavily rewrite hostile mob behavior may require extra compatibility work.

Optional TaCZ interaction may be used for gunfire noise behavior, but TaCZ is not required to run the mod.

Beta Notice

This is a beta release.

The core systems are playable, but balance and behavior may still change based on feedback. Horde sizes, escalation speed, siege pressure, compatibility, and performance defaults may be adjusted in later versions.

Feedback is welcome, especially about:

Horde size balance
Performance in survival worlds
Base siege behavior
Compatibility with other zombie or combat mods
Difficulty preset tuning

Requirements

Minecraft 1.20.1
Forge 47.4.10 or newer