Game WQ : L4D2

Like its predecessor, Left 4 Dead is set shortly after a worldwide pandemic of an infectious disease that rapidly transforms humans into zombie-like creatures and mutated forms that demonstrate extreme aggression towards non-infected (much like the infected in 28 Days Later). Few humans are immune to the disease, still carrying the infection but showing no symptoms. The Civil Emergency and Defense Agency (CEDA) and the U.S. military create safe zones to attempt to evacuate as many American survivors as possible. Left 4 Dead 2 introduces four new survivors—Nick, Ellis, Coach, and Rochelle, who are immune to the disease and have individual back stories that are provided through character dialogue. Like the first game, the five campaigns in Left 4 Dead 2 are set across a story arc, set in the Southern United States, which starts in Savannah, Georgia, and ends in New Orleans, Louisiana. The four survivors have to fight their way through the hordes of infected, using safehouses along the way to rest and recuperate in order to reach extraction points.
After climbing to the roof of a hotel in Savannah to be rescued, the survivors find themselves abandoned by rescue helicopters, and make their way to the local mall, after hearing word of a second CEDA evacuation point there. After a brief encounter with a gun store owner, Whitaker (voiced by Dayton Callie)the survivors discover that the mall is overrun and all of the CEDA agents have either been killed or have become infected themselves. The four then use a stock car to bust out of the mall and travel towards New Orleans ("Dead Center"). On their way there, they encounter the original survivors featured in Left 4 Dead at the portside town of Rayford ("The Passing"), who allow them to cross the bridge by first filling up its generator with gasoline. Later, they find the highway completely blocked by wrecked vehicles and are forced to travel through a still-operating but abandoned amusement park, and start a huge fireworks-and-lights show used by the rock band, The Midnight Riders, in order to attract the attention of a helicopter pilot ("Dark Carnival").
After being rescued, they realize their pilot has been infected. Nick is forced to kill him, which causes the helicopter to crash into a bayou ("Swamp Fever"). They find brief shelter in a plantation mansion and make radio contact with a Cajun boat captain named Virgil who can get them to rescue, but he needs additional diesel fuel to make it to New Orleans. Amid a torrential downpour, the survivors go ashore, make their way through an abandoned sugar mill to a gas station to get fuel supplies, and return to the boat ("Hard Rain"). Virgil takes them to New Orleans where the military appears to be evacuating civilians. The group head to the extraction point, but discover that the military is actually bombing helicopter leaving the city before the bridge is destroyed by an air strike. Judging from their dialogue, the military pilots suspect that the survivors are "carriers" ("The Parish"). Although the survivors' fate after evacuation is left unexplained after the bridge finale, Chet Faliszek, the game's writer, said that the military is taking survivors to cruise ships in an attempt to escape the worldwide infection.
The Sacrifice campaign takes place before the main events of Left 4 Dead 2, sometime before the events of The Passing. The survivors from the Left 4 Dead arrive at the portside town of Rayford in order to search for a boat that could take them to the Florida Keys. After finding an adequate vessel, the survivors manually have to start up generators in order to lift a bridge for their boat to pass through. One survivor (canonically Bill) sacrifices himself in order to kick-start a generator once the lift jams, so that the others may reach safety. This is the end of Bill's story in the Left 4 Dead video game series.

Like its predecessor, Left 4 Dead 2 is a first-person shooter with a heavy emphasis on cooperative gameplay. The game presents five new campaigns, each composed of three to five smaller maps. In the first two to four maps of any campaign, the survivors attempt to reach a safehouse, while the final stage requires the survivors to call for rescue and either survive a prolonged onslaught until rescue arrives, pass through an especially challenging gauntlet of infected to reach a rescue vehicle, or collect and deploy fuel cans to facilitate an escape.
Each survivor can carry one main weapon, and either a melee weapon or pistols as a secondary weapon. Though melee weapons cause extra damage to the infected when struck, the survivors can use any other weapon or item for weaker melee attacks and to temporarily push the infected back. Players also carry a flashlight which has infinite battery and makes it possible to see in the dark, but also causes infected to notice the survivors much faster. They may also carry a single first aid kit, special ammo pack, or a defibrillator; in addition to either pain pills or adrenaline shot. They may also carry a single throwable weapon—Molotov cocktails to set an area on fire, pipe bombs to attract any nearby infected to the flashing light and sound it makes until it explodes, and Boomer bile, which can be thrown at infected to cause them to turn on each other.
Because many of the special infected can quickly finish off a survivor if they are not rescued, the game encourages players to stay and work together to traverse the level safely. To enable situational awareness of other players, players are shown the health and status of their fellow survivors. If a player does not have direct sight of another survivor, they will be shown the survivor's highlighted silhouette. As they take more damage from the infected, players move slower. If a survivor's health drops to zero, they become incapacitated and can only fight off the infected using pistols—even if they are carrying a melee weapon—until rescued by another survivor. If a character dies, they remain dead until the next level, unless revived by a defibrillator, or, in Campaign or Single-player mode, reappear in a "rescue closet" to be freed by the other survivors. Should all the survivors be killed or incapacitated, or if all the human-controlled survivors die, the game is over, and players must restart that chapter.
Left 4 Dead 2 retains the three game modes of the original game—Campaign, Versus, and Survival—and adds a new game mode called Scavenge. In Campaign mode up to four human players fight against the computer-controlled infected to make their way between safe houses; any survivor not controlled by a human player is controlled by the computer. In Versus mode up to four other human players take control of the various Special Infected who try to prevent the Survivors from reaching the next safe house. Special Infected are randomly assigned and one player typically controls a "non-pinning" infected which cannot "trap" a survivor (such as a Boomer or Spitter). Occasionally, as determined by the "AI Director", players will become the Tank, who has a massive amount of health and strength. The two teams swap sides once per chapter and are scored based on their play through as Survivors. Points are given during chapter progress, the more distance, the more points. If both teams make it to the saferoom with all four survivors, a 25 point tie-breaker is awarded to the team that dealt the most combined damage as special infected. Versus mode typically requires at least 1 human player on each team. Survival mode is a timed challenge where the survivors are trapped in a section of the campaign maps, and try to survive as long as possible against an unending onslaught of infected. In the new four-on-four Scavenge mode, the survivor players are required to collect and use as many of the sixteen gas canisters scattered about a level to maintain the fuel of power generators, while the infected players attempt to stop them.
The game features a realism mode, which can be enabled at any difficulty for either campaign or versus modes. This mode removes some of the video-game aspects from the gameplay: survivors are not able to see the silhouettes of their teammates; if they die, they can only be revived with a defibrillator kit and will not respawn later in the level. Damage dealt to Infected is also changed, with headshots dealing more damage to enemies, whereas limb or body shots require more shots, making gameplay even more of a challenge. Additionally, the Witch will now kill any survivor it would have merely incapacitated. Items such as defibrillators, throwable items and weapons will only glow when the player is within a few feet, forcing the players to investigate more thoroughly. Designed to force players to work closely together and rely on voice communication, the realism mode was created to give players a way "to be challenged as a team" without having to increase the difficulty level of the game.

Left 4 Dead 2 features a new cast of human survivors, which include Coach (voiced by Chad Coleman), a portly high-school football coach with a bad knee (although it does not show in the game); Nick (voiced by Hugh Dillon), an unemotional, sarcastic, and rude gambler and con artist; Rochelle (voiced by Rochelle Aytes), a low-level production assistant reporting on the evacuation for a local television station; and Ellis (voiced by Eric Ladin), a laid-back (and rather talkative) friendly mechanic who will talk about his friend "Keith" and his many adventures with him. We learn that Keith escaped via helicopter. While the game is intended as a continuation of the original, occurring one week after the first game begins, Valve decided to create a new group of survivors because of the change in location. In addition to the four playable characters, Left 4 Dead 2 also features a supporting character in the form of Virgil (voiced by Randall Newsome), a Cajun boat captain, who appears (voice only) in the game's final two campaigns. This differs from the original game, where NPCs made little more than a single appearance.

Coach fighting an infected CEDA worker in a hazmat suit

The infected in Left 4 Dead 2 are largely unchanged from Left 4 Dead. While also referred to as zombies, the infected are humans that have contracted a mutated strain of a virus, though neither the source nor nature of this infectious agent are made clear. The most numerous infected encountered by the survivors are the "common infected." Though individually weak, they can swarm and overwhelm the survivors. Damage to the infected In Left 4 Dead 2 is portrayed more realistically, with bullets ripping off bits of flesh and, in some cases, limbs. A new addition to Left 4 Dead 2 is the "uncommon infected" unique to each campaign. By virtue of equipment worn before infection or mutation they possess an ability that separates them from the common infected. In the Parish campaign, for example, the player encounters infected security personnel wearing riot gear, making them almost impervious to gunfire from the front, in the Dark Carnival campaign there are infected clowns who will attract other common infected with the squaking of his nose, while Dead Center features infected civil emergency agents with hazmat suits which are immune to fire.
As in the first game, there are "special" or "boss" infected in addition to the common infected whose mutations grant them special attacks that make them much more dangerous. The presence of such infected nearby is hinted at by sound effects or musical cues unique to each type. The five special infected from the first game return in Left 4 Dead 2, some with modified behavior and skin models. They are: The Boomer, a bloated infected whose vomit and bile (which may be released at will and upon death) blinds the player briefly and attracts a horde of common infected; The Hunter, an agile infected that can pounce on survivors from great distances and screams at the sight of a survivor; The Smoker, an infected that can ensnare survivors with its long tongue from a distance and, upon death, releases a cloud of smoke that obscures vision; The Tank, a gigantic, muscular infected that can punch survivors and toss concrete slabs.; The Witch, a trapper infected who, when provoked by loud sounds, light, or proximity of survivors, will attack her provoker—she is able to incapacitate or kill in one hit. In Left 4 Dead 2, the Witch now has the ability to wander aimlessly in daylight.
Several new Special Infected are introduced in Left 4 Dead 2, all of which are playable in versus and the new Scavenge game mode. The Charger, an infected with an enormously mutated right arm, can charge into the survivors and seize and separate one survivor from the others whilst pummeling them into the ground, rendering the player helpless until one of their teammates helps them. The Spitter can project balls of stomach acid that splatter across an area, quickly eroding the survivors' health as long as they remain within it; the longer a player loiters, the faster their health drops. The Jockey can jump onto the back of a survivor and steer them into other infected or environmental hazards, whilst clawing at the player's head.
In introducing the new Infected, the development team had to consider how the new abilities would mesh with the existing Infected and any changes they had made to them. One discarded idea for a new Infected included the "Leaker"; the creature, when having taken damage, would shoot out spouts of goo at the survivors, and then would be able to self-detonate like the Boomer. However, this sacrificial act would have given survivors time to escape, and the idea was dropped, though features of the Leaker were built into the Spitter.