Left 4 Dead

Left 4 Dead, or L4D, is a video game series exclusive to the Xbox 360 console and PCs. The storyline of each game follows four people (the Survivors) as they attempt to fight their way through waves of zombies (called Infected). Several types of Infected have special abilities in order to make them a greater challenge for the players. The first game was released in 2008 to predominantly positive reviews. The sequel, which included four new Survivors and three new types of Special Infected, came out a year later.

Gameplay usually involves teaming up with three other players in order to get through one of the specific campaigns. There is also a versus mode, where players are both Survivors and Special Infected.

Special Infected
There are eight difference types of Special Infected, seven of which are playable in multiplayer verses mode. Agents operating in this continuum will often disguise themselves as one of these creatures. In alphabetical order, they are:
 * The Boomer, a morbidly obese Infected that vomits bile onto Survivors. The bile obscures their vision and attracts ordinary Infected. When killed, Boomers explode and cover any Survivors near them with more bile.
 * The Charger (introduced in Left 4 Dead 2) is a large and fast Infected that picks up Survivors with an oversized arm and runs off with them until it hits a wall or other surface. It then proceeds to smash the Survivor against the ground,
 * The Hunter, an Infected in a hooded sweatshirt who leaps onto Survivors and rakes them with his claws. Hunters are extremely quick and capable of jumping great distances.
 * The Jockey (introduced in Left 4 Dead 2) can jump onto the backs of Survivors and steer them away from their friends into hazards or towards other Special Infected.
 * The Smoker, who can constrict and strangle Survivors with an extendable tongue. They are called 'Smokers' due to their coughing and their ability to give off a field of obscuring smoke with killed.
 * The Spitter (introduced in Left 4 Dead 2) is a female Special Infected with a spitting power similar to the Boomer. Instead of bile, however, Spitters emit acid that can damage Survivors who accidentally stand in it. Her lower face and jaw are melted as a demonstration of how powerful the acid is.
 * The Tank is a roaring hulking monster, able to send Survivors flying with a single punch. Tanks are also capable of tearing chunks of concrete from the ground and hurling them at Survivors out of arms reach. It can take up to or over a minute for a Survivor to take down a Tank. His arrival in the game is always punctuated by a dramatic music cue.
 * The Witch is a female Special Infected, and the only one to not be controlled by players. Her appearance is that of an emaciated girl in her underwear with white hair and long claws. Her appearance will be punctuated by the sounds of her sobbing. She will be found sitting on the ground, hiding her face and crying. If she is startled by a flashlight or gunfire, she becomes enraged and will attack the Survivor who startled her. Quiet and careful Survivors may be able to sneak past the Witch.

Left 4 Dead and the PPC
Fanfiction about Left 4 Dead is often split between Mary Sue/Marty Stu survivors (or sometimes infected) and slash. Any L4D slash is typically between Survivors (Nick/Ellis from L4D2 being very popular), but there is also a great deal of femslash between Zoey from the original L4D and the Witch.

Missions in Left 4 Dead
There have not yet been any missions in the L4D continuum.