Left 4 Dead 2 is a cooperative first-person shooter video game developed and published by Valve Corporation. The sequel to Turtle Rock Studios's Left 4 Dead, the game released for Microsoft Windows and Xbox 360 in November 2009, and for OS X in October 2010, and for Linux in July 2013.
Left 4 Dead 2 builds upon cooperatively focused gameplay and Valve's proprietary Source engine, the same game engine used in the original Left 4 Dead. Set during the aftermath of an apocalyptic pandemic, Left 4 Dead 2 focuses on four new Survivors, fighting against hordes of zombies, known as the Infected, who develop severe psychosis and act extremely aggressive. The Survivors must fight their way through five campaigns, interspersed with safe houses that act as checkpoints, with the goal of escape at each campaign's finale. The gameplay is procedurally altered by the "AI Director 2.0", which monitors the players' performance and adjusts the scenario to provide a dynamic challenge. Other new features include new types of special infected and an arsenal of melee weapons.
The game made its world premiere at E3 2009 with a trailer during the Microsoft press event. Prior to release, it received a combination of positive and negative critical and community reactions. It attracted an unusually high volume of pre-release controversy about the game's graphic content. In response, alterations were made to the cover art and both Australia and Germany refused to rate the unmodified edition at the time of release. After release however, the game was met with positive reviews by critics.
Like its predecessor, Left 4 Dead 2 is set in the aftermath of a worldwide pandemic of an infectious disease known as the "Green Flu", which 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—Coach, Ellis, Nick, and Rochelle, who are immune to the disease and have individual back stories that are provided through character dialogue. 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 due to the change in location. Like the first game, the five campaigns in Left 4 Dead 2 are set across a story arc, set in theSouthern United States, which starts in Savannah, Georgia, and ends in New Orleans, Louisiana. The four Survivors have to fight their way through hordes of Infected, using safehouses along the way to rest and recuperate in order to reach extraction points.
While also referred to as zombies, the Infected are humans who have contracted a mutated strain of an infection, though neither the source nor nature of this "Green Flu" are made clear in the games. The most numerous Infected encountered by the survivors are the common Infected. Though individually weak, they can swarm and overwhelm the Survivors, especially when separated from their teammates. Damage to the infected in Left 4 Dead 2 is portrayed more realistically, with bullets and melee weapons 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 location and equipment worn pre-infection, they possess abilities that separate them from the Common Infected. For example, the Dead Center campaign introduces infected CEDA agents in hazmat suits, making them fireproof; Dark Carnival includes clowns, whose squeaking shoes attract small hordes of Common Infected; and The Parish includes infected private security contractors in riot gear, making them bulletproof from the front.
As in the first game, there are special Infected whose mutations grant them special abilities that make them highly dangerous, which act as bossess. 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:
· The Boomer: an extremely bloated Infected who vomits bile. The bile attracts a horde of Common Infected on contact with Survivors and also momentarily blinds them.Upon death, it explodes and can also spray bile onto nearby Survivors.
· The Hunter: an agile male Infected that can pounce on and incapacitate Survivors from great distances, tearing at them until the Survivor dies or another Survivor shoves it off/kills it.
· The Smoker: a male Infected with a long tongue that it uses to ensnare Survivors from a distance, continually choking them. Upon death, it releases a cloud of smoke that can obscure the Survivors' vision and cause them to cough, should they come in direct contact with the smoke.
· The Tank: a gigantic, extremely muscular Infected male with the strength to punch Survivors off their feet some distance, as well as toss cars and concrete slabs. Unless the Survivors work as a team, they will be quickly incapacitated or even killed by the Tank's inhuman strength.
· The Witch: a crying Infected woman who, when provoked by either damage, loud sounds, light, or proximity of survivors, will attack the provoker and any other Survivors after her provoker is dead. She can incapacitate or even kill a Survivor in one hit. Left 4 Dead 2 introduces a variant of the Witch that wanders aimlessly in the open.
Left 4 Dead 2 also introduces three new Special Infected:
· The Charger: a male Infected with an enormous right arm, and can charge into the Survivors, capturing and carrying one Survivor away from the others, sending any others in his path flying to the side after a capture and stunning survivors upon hitting an obstacle in a charge. He may then pummel his captured Survivor into the ground, rendering that Survivor helpless until one of their teammates helps them by killing the charger or stunning it with frag rounds.
· The Spitter: a female Infected that spits out balls of stomach acid that splatter across an area, quickly eroding the Survivors' health as long as they remain within it. She also leaves a puddle of goo upon death. The longer a player loiters in the goo, the faster their health drops.
· The Jockey: a male Infected that jumps onto a Survivor's back and steers them into other Infected or environmental hazards (e.g. Spitter goo), whilst clawing at the player's head until the player is incapacitated, killed, or shoved off.