Zomtorio

Turns Factorio's biters into an overwhelming zombie horde. Enemies come in far larger numbers and are individually much weaker — a swarm to be mown down, not a handful of bullet-sponges. Your destroyed buildings become sources of new zombies, infection creeps through your factory along the flow of goods, and the dead don't always stay dead.

Important tips

• Melee attacks exist (attack with no ammo left), and research the upgrades for melee attacks added in this mod.
• Eating a fish clears infection
• Active shields prevent being infected
• Fire or explosion kills prevent zombie corpses reanimating. As does the melee "double tap" ability (once researched, toggle-able like exoskeleton is)
• Zombie corpses can be burnt as fuel, or dried in a kiln, or burnt in a pyre (new building types)

Features at a glance

• Swarm hordes — enemies are weak, slow, and tightly packed, but vastly more numerous; huge numbers are represented cheaply by "horde unit" clusters under a configurable active-zombie cap.
• Buildings become zombie sources — a building the horde destroys spawns zombies equal to its total raw resource cost; walls/gates exempt; your own demolition never spawns anything.
• Infection + contagion — a horde hit infects a building/robot (damage-over-time, cured by full repair) and spreads downstream through the factory along the flow of goods (inserters, loaders, drills, belts), bounded so it never costs UPS.
• Player infection — bites that get through your shields infect you; regen is suppressed until any heal cures it.
• Biohazard alt-mode marker — infected buildings show a red biohazard warning triangle in alt-mode (like the frozen/no-power icons), with no effect on operation.
• Corpses & reanimation — kills drop burnable corpses that reanimate into zombies (spoilage) wherever they sit; kiln-dry them to store safely, at a fuel loss. Fire/explosions leave no corpse.
• Melee tech + Double Tap — researchable swarm multi-kill (two tiers) and a toggle for clean, corpse-free melee kills.
• Night & swarm events — zombies move faster at night; telegraphed, evolution-scaling swarm events strike at night on top of pollution-driven attacks.
• Denser, cheaper enemies — pollution recruits far more attackers, nests and expansion are cranked up, all tunable.
• Fully configurable — see the settings table below.

What changes

The horde

• Enemies are weak, slow, pack tightly, and pursue relentlessly once they have your

scent — but there are *far* more of them.

• Huge numbers stay cheap: a horde unit is a single entity that stands in for a

whole cluster of zombies, carrying a population count. Hit one and it either bursts into individual zombies (if there's room under the active-zombie cap and you're nearby) or simply loses population. Explosives and upgraded melee kill many at once.

• A configurable active-zombie cap keeps UPS in check: overflow folds into

abstract clusters instead of being discarded, so the zombies still exist.

Buildings become zombie sources

• When the horde destroys one of your buildings, it spawns zombies equal to the

building's total raw resource cost (1 zombie per unit of mined ore). Bigger, costlier buildings make bigger hordes. Walls and gates are exempt.

• Destroying your *own* buildings (mining, deconstruction, your own weapons) never

spawns zombies.

Infection

• A single hit from the horde infects a building, robot, belt, or inserter: it takes

damage over time and, if it dies, spawns zombies. Fully repairing it cures it.

• Infection spreads through the factory along the flow of goods — inserters,

loaders and mining drills carry it downstream when they move items from an infected source, and belts carry it along their length while items ride them. A part of the factory with no item movement doesn't spread it. "Let it all die and rebuild" is a valid (brutal) containment strategy.

• You get infected too if a zombie bites through your health (shields protect

you). Infection suppresses your natural regen — but any real heal (a fish, a medikit, anything) clears it.

Corpses

• Killed zombies drop a corpse item that's burnable as fuel — the reward for

fighting this enemy. But corpses reanimate into new zombies on a timer (spoilage), wherever they sit: ground, belts, chests, machines. Burn them or kiln-dry them (a non-spoiling, store-forever form, at a deliberate fuel loss) before they hatch.

• Zombies killed by fire or explosives are destroyed outright and leave no corpse.

Melee & technology

• Your bare-handed punch kills one zombie, as in vanilla. Two technologies grow it:

Tier 1 (automation science) lets melee multi-kill a swarm; Tier 2 (with logistic science) hits harder and unlocks Double Tap — a toggle that makes your melee kills "dead-dead" (no corpse, no reanimation) at the cost of the fuel.

Night & swarm events

• Zombies move faster at night (configurable).
• Telegraphed swarm events ("a swarm approaches in N days") strike at night and

grow with evolution — rarer and brief early on, frequent and lasting the whole night at full evolution — layered on top of the usual pollution-driven attacks.

Settings

| Setting | Default | Effect | |---|---|---| | Horde size multiplier | 1.0 | Overall multiplier on zombies generated. | | Active zombie cap | 1000 | Max individual zombies; overflow becomes clusters (CPU tuning). | | Building infection | on | Buildings hit by the horde become infected. | | Infection time-to-death | 300 s | Time for an infected building (full health) to die (30 s–10 min). | | Player infection | on | Bites infect you; healing cures it. | | Night speedup | +100% | How much faster zombies move at night (startup). | | Corpse reanimation | on | Corpses spoil into zombies (startup). |