Left 4 Dead 1-2

Left 4 Dead is a cooperative multiplayer survival horror and first-person shooter game initially developed by Turtle Rock Studios which, on January 10, 2008, became part of the Valve corporation. The game was built by Valve's Source Engine and is available for PC, Xbox 360 and Mac OS X. A Certain Affinity is responsible for the Xbox 360 version. The release of Left 4 Dead, considered by many to be the most anticipated game of 2008, took place on November 4, 2008 for most of the world; in the UK the game arrived on November 7th. The game was first revealed at Christmas 2006 by PC Gamer UK with a six-page article describing the early strategies of Valve members. The first teaser/trailer for this game is available on the Orange Box and in various places on the internet. Left 4 Dead was first tested on LAN at Showdown 2007 in San Jose and at QuakeCon 2007.

Like Left 4 Dead, the sequel involves an apocalyptic pandemic. There is a leak of a pathogen that causes Infected humans to behave like zombies. The four survivors must fight off the Infected horde. Left 4 Dead 2 is set in the southern United States, starting in Savannah, Georgia and ending in New Orleans, Louisiana. Characters from the original game have been replaced by four new survivors, whose stories are revealed through dialogue. Unlike the first game where there is no significant story development, Left 4 Dead 2 has a backstory. The new campaigns are: "Dead Center", which takes place in a shopping center, "Dark Carnival", where passing through a semi-operating amusement park, "Swamp Fever", where we see the survivors crossing a swamp and "The Parish", which takes New Orleans as its stage.