Mutations

"Each week one new Mutation is featured and the previous Mutation retired."

- Valve

Mutations is the name for a new set of gameplay modes scheduled to appear alongside the new campaign, The Passing in Left 4 Dead 2. The Mutations are special game modes that run for one week before it is retired, and replaced by a new Mutation each week as they become announced on the in-game Blog Post every Thursday. Presumably after all the Mutations have been revealed, a poll will be conducted once a month for players to vote for their favorite Mutation, which will return the following week. It is only available to those who have downloaded The Passing.

Revealed Mutations
There are over 20 different Mutations planned, and playable on all Left 4 Dead 2 Campaigns.

So far, the following have been revealed on Valve's blog in the scheduled order along with their taglines:

Realism Versus

 * You can't see each other but they can see you.

Versus Mode mixed with Realism Mode, favors Infected side

Bleed Out

 * Your health is a ticking away.

No information revealed, scheduled release 30th of April according to new in-game Blog Post

Chainsaw Massacre

 * 4 chainsaws, millions of zombies.

Campaign Mode only, Survivors only have access to Chainsaws with unlimited fuel

Strategies
Note: Waiting for strategies here

Within Script Files
Most of the Mutations are shown within the script files along with their game taglines:


 * Bleed Out - Your health is a ticking away.
 * Chainsaw Massacre - 4 chainsaws, millions of zombies.
 * Follow the Liter - Scavenge one can at a time.
 * Four Swordsmen - Four Swords against plenty of apocalypse!
 * Gib Fest - Blast the infected to shreds with M60s.
 * Hard Eight - Double the specials, quadruple the fun!
 * Headshot! - The only shot that counts is the one in the head.
 * Healthpackalypse! - No health in this versus game.
 * Iron Man - No respawns, no restarts, all tension.
 * Last Gnome On Earth - Protect the gnome at all cost.
 * Realism Versus - You can't see each other but they can see you.
 * Room For One - Only room for one survivor in this rescue vehicle.
 * Ultra Realism - The ultimate realistic challenge.
 * Versus Survival - Can you survive against your friends?
 * Mutation - a Mutation of Campaign mode.
 * Mutation - a Mutation of Versus mode.
 * Mutation - a Mutation of Scavenge mode.

Single-Player only Mutation modes:


 * Last Man on Earth - You will become legend to the infected as the last human left.
 * The Last Samurai – Alone, armed with only a sword you venture forth.