Zombies & the Knox infection

42.15 (March 2026) replaced the old Survivor and Builder presets with four official modes. Apocalypse is the canon “lore” mode.

Full mode-by-mode details are in the beginner’s guide.

Sandbox mode lets you set every option yourself. Defaults per official mode:

The one setting that changes the game most is Speed. Sprinters turn every encounter into a fight; Shamblers make the game about logistics. Random mixes both, so treat every zombie as a possible sprinter.

The Knox infection only comes from zombie wounds, and on default settings it always kills.

Once per game, usually between day 6 and day 9 and between 9 AM and 7 PM, a helicopter circles Knox Country. If it spots you outdoors it follows you, and every zombie that hears it follows too. The Automated Emergency Broadcast on the radio warns “air activity detected” the day before.

1. Listen to the emergency broadcast every morning from day 5.
2. On the warning day, stay indoors with the curtains closed.
3. If it finds you, do not run home: lead it away from your base, then break line of sight inside a building.

The story behind it is on lore and broadcasts.

Our rules.

1. One at a time. Back up through a door so they come to you single file.
2. Shove, then stomp: push a zombie over and stamp its head. It costs no weapon condition.
3. Watch endurance. An exhausted character swings slowly and cannot run.
4. Fight in the open only in daylight, and never near a car alarm.
5. Scratches happen. Clean and bandage at once, then watch for Queasy.

Weapons and skills are on weapons and skills; the moodles you will see are on moodles.

A zombie's clothes were its job. The game places uniformed zombies at the workplaces that match, and the uniform both tells you what might be in its pockets and how hard it is to bite through. Loot on a corpse is never guaranteed, but the odds follow the outfit.

Keys are the other prize: some zombies carry car keys or house keys, and a key from a police or gun-store worker opens the reinforced door you could not break. Searching a corpse takes time in the open, so drag it indoors or behind a wall first. See clothing for protection values and bags for the packs.

Zombies do not stand still between your visits. Three systems move them, and the numbers behind each are plain sandbox values you can read or change.

Rally groups. Idle zombies clump into groups of up to 20 (Rally Group Size), stand within about 3 tiles of each other (Rally Group Radius), keep roughly 15 tiles between groups (Rally Group Separation) and wander about 20 tiles from where they formed (Rally Travel Distance). That is why a street looks empty and then has twenty zombies around one corner: the group is the unit, not the individual.

Redistribution. Every 12 hours on Apocalypse and Outbreak, and 18 on Rising, the game shuffles the living population between cells. Respawn is off on Apocalypse and Outbreak; Extinction and Rising respawn on a 72-hour cycle at a tenth of the original density, and Six Months Later at half. Clearing a town on Apocalypse is therefore real, but zombies from next door will drift in to replace some of them.

Noise. Sound is what turns groups into a horde. Zombies walk towards the last sound they heard for up to the Follow Sound Distance, 100 tiles by default. Gunshots are the loudest thing you own: with the Firearm Noise Multiplier at 1, shotguns carry about 200 tiles, hunting rifles around 170, assault rifles around 150 and pistols about 100. A car alarm or house alarm runs until the battery or the siren timer gives out, a running generator and a car engine are steady draws, and hammering carries about 15 to 20 tiles. Shouting, sprinting and breaking glass are small in comparison but enough to wake the next group. The helicopter, dogs and distant gunfire are metagame events that drag whole hordes across the map, often straight through your base. See weapons for noise by gun.

A horde that has lost you does not go home; it lingers. The second loud noise in the same place an hour later is the one that gets people killed.

Every body you drop is a problem that gets worse. In Build 42 decaying corpses feed the same sickness track as food poisoning, so a kill pile outside your window can take you from Queasy to Nauseous, Sick and Fever if you stay in it. The pressure only starts once more than five corpses are near you and the Decaying Corpse Health Impact setting is not None (it defaults to Normal), and it stops building as soon as you leave the area or get the count down to five. Piles also throw the separate Noxious Smell moodle, which climbs from Bad Smell to Deadly Fumes, and the 42.22 Pre-Release notes say you cannot sleep while Bad Smell is showing. A gas mask with a working filter blocks the fumes while you clear up. See moodles and health.

Corpses disappear on their own after 216 in-game hours, nine days, on the default Time Before Corpse Removal; set it to 0 and they stay forever, and maggots stop spawning. Nine days is too long to live next to, so you have three options.

1. Drag them away. Grab a corpse and walk it a street over. Slow, silent and free; the sickness is about proximity, so distance is a cure.
2. Burn them. Pour petrol on the pile and light it with a lighter or matches. Fast and final, but fire spreads to grass, fences and your own walls, and the smoke is visible. Burn in a car park or on a road, never beside the base.
3. Bury them. Dig a grave with a shovel, drop the bodies in and fill it. Quiet and safe, and each grave takes several corpses. Good for the inevitable bodies at your gate.

Fight away from home when you can. The simplest disposal plan is to make the kill pile somewhere you do not sleep.