Sprinters and zombie lore settings in Project Zomboid

Zombie speed is set under Custom Sandbox, Zombie Lore, Speed. Build 42 has four choices. Crawlers are not one of them: a crawler is a zombie on the ground, whatever its speed setting. See zombies for the basic types.

Random Sprinter Amount is the percentage option. It runs from 0 to 100 and only does anything when Speed is Random. At 0, Random gives a mix of slower zombies with no runners, which is what Apocalypse uses. There is one percentage box, for sprinters only. I found no separate box for the share of fast shamblers and shamblers, and no patch note saying which Build 42 update added the setting. Build 41 had Random but not this control.

Extinction, added in update 42.15, is the first official mode with sprinters, in the developers' own words. The preset values below were read from the game files by two fan sites, and they agree. For the rest of each preset, see game modes.

Six Months Later stores 33 in the sprinter box, but its Speed is Fast Shamblers, so the number should not apply. If you switch that preset to Random, expect a third of zombies to run. The 28 Seconds Later challenge arrived in 42.20 and is described officially only as a world full of sprinting zombies.

Six percent sounds small. In a group of 50 it is about three runners, and they reach you well before the rest, already separated from the pack.

Speed is one line of 29 in the Build 42 Zombie Lore tab. These are the ones that matter most with sprinters. Option counts and preset values come from a 42.22 file readout (one source). The full list is on sandbox settings.

• Strength affects damage and door breaking, and Drag Down depends on it. Superhuman sprinters are the worst case.
• Cognition at Navigate + Use Doors lets zombies open unlocked doors. With Random, the door percentage appears to set how many can. The game gives that box no description, so this is read from its name.
• Memory is how long a zombie keeps chasing after it loses you. Long memory plus sprinters makes breaking line of sight much less useful.
• Smell is not in the Build 42 list. Server guides that still show a Smell line were written for older builds.
• Day or night activity: the in-game text only says zombies are more active in the chosen period. Build 41 players reported that fast shamblers slow to a crawl in the inactive period while sprinters kept running (one source). Test it before building a run on night-only sprinters.

Opinion The rule that changes is the oldest one. Against shamblers you walk away and pick your fight. A sprinter picks it for you, so plan every trip around never meeting more than one or two at once.

• Stealth first. Crouch, stay out of sight lines, and keep the New Stealth System on so cars and low cover hide you. See stealth.
• Face them. A runner hitting your back is what kills. Stop, turn, shove or swing as it arrives, then finish it on the ground. Timing is covered in combat.
• Use long, quick weapons. Spears and long blunt weapons reach a runner before it reaches you. Compare reach and speed on the melee list. Keep stamina in reserve, since a tired swing misses the one hit you get.
• Guns are a last resort. One shot can pull every runner in earshot, and Extinction zombies follow sound twice as far as Apocalypse ones (one source). See firearms.
• Fight in doorways. A door frame feeds them to you one at a time. One guide calls one sprinter in a frame manageable and two lethal (one source). Close doors behind you. With basic cognition a shut door buys time even though it will be beaten down.
• Keep a car close. Park facing out, engine in good order, and loot in short trips. A car outruns anything, but it is a delay and not a wall once it stops. See vehicles.

Opinion Pick a base for escape routes before defenses. The checklist on base locations still applies, with these changes.

• Live upstairs. A second floor with the stairs removed and a sheet rope down keeps runners out. More on base building.
• Do not rely on a quick fence hop. Zombie Lunge is on in every preset except Rising, so a zombie that follows you over a fence or through a window can lunge if you stand too close.
• Tall fences fail to crowds. Apocalypse needs 25 zombies at a fence before it takes damage and Extinction needs 20 (one source).
• Keep two exits and a clear run to the car. Cover windows so light and movement do not draw the first runner.

Opinion Do not start with Speed set to Sprinters. Start from the Apocalypse preset and change only a few lines, so you learn runners without Extinction's superhuman strength and thin loot.

Take a character with good Fitness and a fast weapon skill. The character builds page has options. Once a week feels routine, raise the percentage before touching strength.

A server uses the same options. Hosting from the main menu shows the normal sandbox screens. A dedicated server reads them from Zomboid/Server/[servername]_SandboxVars.lua, inside the ZombieLore block. Speed takes the numbers in the first table, so Extinction-style runners are Speed = 4 with SprinterPercentage = 6. The door share is DoorOpeningPercentage.

Stop the server before editing the file. An admin can also change a value live with the /changeoption command, but that change is lost on restart unless the file is edited too (one source). Sources disagree on whether zombies already loaded switch speed on an old save, so test on a backup.

Sprinters reached Build 42 multiplayer in update 42.17, where press coverage called them a prototype. I found no statement that the label has been dropped. Runners also cost more server performance than walkers (one source). Setup steps are on hosting a server and multiplayer.