How do I set a mutation on a Left 4 Dead 2 server?

Open the web console on your server and run: sm_cvar mp_gamemode mutation4 ; changelevel c1m1_hotel (swap mutation4 for the mutation id you want and c1m1_hotel for any campaign map). The mode only applies on the next map load, so you chain a changelevel.

Can I play Hard Eight with 8 players in L4D2?

Yes. Hard Eight (mutation4) sets the survivor limit to 8. To seat 8 real people rather than bots you also need the raised player cap, which our Large tier provides, so the eight survivor slots can all be humans.

What is the difference between a mutation and a game mode?

Game modes are the four base ways to play (Co-op, Versus, Survival, Scavenge) plus Realism. Mutations are official challenge twists on top of those, such as melee-only or headshots-only, that Valve used to rotate weekly. On your own server you can run any of them any time.

Left 4 Dead 2 mutations: Hard Eight, Gib Fest, and how to set them

Left 4 Dead 2 mutations mp_gamemode hard eight realism versus gib fest 8 player ems

Updated Sep 22, 2026

Mutations are Left 4 Dead 2’s challenge modes: melee-only runs, headshots-only, eight survivors at once, versus with the training wheels off. Valve used to rotate one into official matchmaking each week, so you played whatever was live. On your own server there is no rotation: you set any mutation you want, any time, and keep it. Here are the ones worth playing and how to switch them on.

How to set a mutation

Open the web console on your server card. The Mode dropdown covers the base modes (co-op, versus, survival, realism, scavenge). A mutation is set the same way, by its id, in the command box:

sm_cvar mp_gamemode mutation4 ; changelevel c1m1_hotel

Swap mutation4 for the mutation you want and c1m1_hotel for any campaign map. The mode only takes effect on the next map load, which is why you chain a changelevel. Full command list in the commands guide.

The mutations worth playing

Every mutation has an id you pass to mp_gamemode. The popular ones:

Campaign twists

Hard Eight (mutation4): eight survivors instead of four, with more special infected to match. The party mode, see the 8-player note below.
Gib Fest (mutation14): everyone gets a grenade launcher and melee weapons. Loud, gory, and very fast.
Bleed Out (mutation3): you start on temporary health that ticks down the whole level, with no pills to top up. Race the map before you bleed out.
Headshot! (mutation2): only headshots kill common infected. Pure aim discipline.
Four Swordsmen (mutation5): melee only, four katanas, no guns. Chaos in tight corridors.
Chainsaw Massacre (mutation7): everyone starts with a chainsaw that never runs out of fuel.
Last Man on Earth (mutation1): solo, no survivor bots, and ammo and health are scarce. The hardest way to play a campaign.

Versus twists

Realism Versus (mutation12): competitive Versus with Realism rules on top: no teammate outlines, tougher witches, no rescue closets.
Versus Survival (mutation15): two teams trade off holding a survival arena and compare times, instead of running a campaign.
Healthpackalypse! (mutation11): no medkits anywhere on the map. Every point of health matters.
Taaannnkk! (mutation19): every infected player spawns as a Tank. Non-stop pressure on the survivors.

Hard Eight with a real 8-player team

Hard Eight (mutation4) raises the survivor limit to eight, but in a normal lobby the four extra seats fill with bots. To make all eight real people you also need the raised human cap. Deploy on the Large tier and open up the player slots, then eight of you drop into the same campaign together. How to play with more than 4 players.

Custom mutations from the Workshop

Beyond the official list, the Extended Mutation System (EMS) lets creators publish brand-new mutations as Workshop add-ons: horde nightmares, boss rushes, entirely new rulesets. Load one exactly like a custom campaign (everyone subscribes), then set mp_gamemode to the mutation’s id. Playing custom Workshop content.

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