Dead Air

Dead Air is the fourth campaign in Left 4 Dead. Initially it was the third campaign in the game, but has become the fourth after the release of Crash Course.

Dead Air was also ported to Left 4 Dead 2. Valve released this campaign for the sequel on July 22, 2011, after 20,000 Left 4 Dead 2 players earned the achievement "STREAM CROSSER" by completing the campaign Cold Stream. The remake features weapons, items and Infected from the latter game. In addition, significant changes were made to the campaign, most notably the one-way drop in The Construction Site and the gauntlet crescendo in The Terminal.

The campaign opens with the Survivors hiding in a rooftop greenhouse when a low-flying C-130 sparks the idea that the local airport may still be operating evacuation flights. Thereafter, the campaign has The Survivors make their way through Newburg to Metro International Airport where they must refuel their escape aircraft.

To get to the airport they must traverse rooftops, apartment buildings, and office cubicles; they defy health and safety regulations by lowering a dumpster using a crane, shoot their way through a de-constructed construction site, surmount the manifold dangers posed by an electrical substation, find somewhere safe in short-term airport parking, deliver various keynote addresses at the airport's conference center, attempt to check in, discover what really happens to lost airline luggage, battle crowds in the departure lounge, check their economy boarding passes before proceeding to the departure gate, and (in true budget airline tradition) ensure the airplane is prepped to fly before finally boarding their flight through the rear exit.

Below is a complete list of video walkthroughs of the 5 levels:


 * 1) The Greenhouse
 * 2) The Crane
 * 3) The Construction Site
 * 4) The Terminal
 * 5) Runway Finale

Please note that the gameplay videos are on each campaign's info page, not on each map page.

Left 4 Dead 2
With the Cold Stream DLC mentioned above, Dead Air was edited and ported to Left 4 Dead 2. Thus, it included all the new Infected, items and weapons, giving a whole new experience. Video walkthroughs made by YouTuber Rusty Woud show off the Left 4 Dead 2 version of the campaign and all changes from the original version:
 * 1) Maps 1 and 2
 * 2) Maps 3 and 4
 * 3) Map 5

Official description
Guide your team of Survivors out of the downtown core of Newburg's business district, through derelict office floors and still-inhabited cubicles, and out onto the runway of Metro International Airport, where the only thing standing between you and the last plane out of the city is a murderous army of the undead.

Graffiti

 * There are several instances on the rooftops where one may find writing, such as "Help! Need food," or "S.O.S." There are also numerous writings about how a bomb will be dropped on the airport.
 * The Terminal's starting safe room contains some of the game's most memorable graffiti including: "WE ARE THE REAL MONSTERS" and "I miss the internet".
 * Other notable inscriptions include claims that the Infected were created by the military, the government is giving a cure to the rich and that the virus was made by aliens. Subsequent refugees have added their own disparaging addenda to these assertions.
 * The phrase "God is dead" can be seen at various places in the campaign. Zoey will occasionally make an ascerbic comment about it when she reads the one that appears on a wall at the airport conference center. This statement was coined by the German philosopher Friedrich Nietzsche and has since become embedded in popular culture as a way of rationalizing events of mass horror and disaster. The phrase also appears as a line in the final act of The Crucible.
 * In the safe room of The Crane, there is some graffiti on the wall that states "This is our punishment." Right under this is the sentence "It's just Dead Air"―a reference to the title of the campaign.

Achievements

 * See Main Article: Achievements

Behind the Scenes
Only one screenshot of Dead Air was shown before the game was released. This, together with an early Runway image in the game's files suggests that Dead Air was originally intended to have a light blue "moonlight" visual tint applied to it.

An unreleased map called "Tutorial Standards" also exists in the both Left 4 Dead games' files which was originally intended to be part of the third chapter of this campaign with the title "The Garage".