Dead Air

Dead Air is a five-chapter Left 4 Dead campaign. On first release, it was the third campaign in the game but moved to fourth position in the wake of the subsequent issue of the Crash Course campaign.

The Dead Air campaign is also being ported over to Left 4 Dead 2. The beta was released July 22, 2011 due to Valve's promise if 20,000 Left 4 Dead 2 players earned the achievement "Stream Crosser" by completing the Cold Stream Campaign. The beta features the melee weapons from Left 4 Dead 2; however, Valve also mentioned that they have changed chapters 4 and 5 of the campaign.

The campaign opens, somewhat bemusedly, 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 follows the challenges and travails of The Survivors as they make their way through Newburg to its Metro International Airport.

Along the way, they must traverse rooftops, apartment buildings, office cubicles, 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 know that the gameplay videos are on each campaign's info page, not on each map page.

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.
 * In The Terminal's starting safe room, a piece of graffiti states, "WE ARE THE REAL MONSTERS" on the wall, along with various other messages below it telling the writer that they are a moron, telling them that the Infected are the real monsters, and somebody even tells them that he wishes that they are dead now.
 * On the same wall, written in small letters, is the famous graffiti, stating, "I miss the internet".
 * In one sentence, it claims that the Infected were created by the military. Following that, there is a rumor that the government is giving a cure to the rich. Below that is a claim that the virus was made by aliens, along with a writing saying "What if this was first contact?" followed by "What if you're an idiot?!"
 * Rare appearances of Infected military personnel can sometimes be glimpsed just outside the Greenhouse.
 * Several times throughout the campaign, the phrase "God is dead" can be seen. This was a statement originally made by the German philosopher Friedrich Nietzsche, and has heavily been quoted since. However, the phrase could have also been a reference to a line in the final act of, The Crucible. Occasionally, the Survivors may respond to the writings, saying things such as, "Oh, no! The zombies killed God!"
 * 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. On this basis and an early Runway image in the game's files, it is evident that Dead Air was originally intended to have a light blue "moonlight" visual tint.

There is also an unreleased map called tutorial_standards that was originally going to be part of this campaign as the Dead Air poster can be seen at the end of this level. This also works with Left 4 Dead 2. And another one is called "map c5m1_waterfront_sndscape". (The second one only works with Left 4 Dead 2)

Originally, the third chapter was called "The Garage".