Air Exchange

"She pointed out a mounded shape, just visible through the enveloping smog; it looked like the shell of a vast slumber beetle; a streamlined mountain of corroded metal. From the density of the fumes, the stink of the air and the burning in his eyes, he suspected he had arrived at what Eli had called, "The Air Conditioner"."

- Alyx Vignette

The Air Exchange, also known as Air Conditioner, AirEx or Combine's atmospheric reprocessor, is a location and chapter cut from Half-Life 2. It was to be set after the Depot, at the end of the Wasteland / Coast chapters, and before the Borealis, as the penultimate location of the third day. Prototyped and having all its maps made (although they are very messy and hard to fix), it was never finalized to let the team concentrate on areas more fruitful for gameplay.

Overview


Like the Citadel and the Depot and possibly the Weather Control, the AirEx was to be one of the many Air Exchanges spread on Earth by the Combine.

Similar in the surface to common Earth factories, it was to be a Combine facility guarded by Combine Soldiers and Stalkers that was to replace the air by noxious, murky gases with its main reactor powered by an unknown blue energy source, probably the storyline predecessor of the Dark Energy. Most of the air of the region was to be highly toxic, and most of the City 17 inhabitants were to wear gas masks. As leader of the Conscripts, Captain Vance was to play a compromised and dangerous role protecting the facility (" " also features several visgroups named after Vance, and a command center). Trucks of unknown use were to be found in the facility, along with refineries. Barnacles and Zombies were also to be found in several areas.

In this chapter, early concepts have Gordon Freeman arriving by train and crashing into a small depot located before the facility. There he was to meet Alyx and her pet alien Skitch. Then they would be attacked by Striders and Combine Super Soldiers.

While Vance and his Conscripts were to launch an attack on the Weather Control, three chapters after the AirEx chapter, it is likely that some battle was to take place at the very start of the chapter, outside and inside the AirEx, since Vance was to protect the facility. It is also said that Eli Maxwell was the first to mention the AirEx existence to Gordon, probably in his slideshow.

Inside the facility, Gordon was to reach the top of the industrial tower where seems to be located a control room and battle a Gunship and then jump into a pool of industrial solvents at its base. Then he was to go inside the main reactor of the facility, protected and operated by Stalkers, and sabotage its core (its design is almost identical to the Lambda Core from Half-Life), making the Air Exchange completely nonoperational and triggering the human uprising in City 17. Then, Gordon was to reach the shore on foot and proceed to the Borealis with Odell on a tugboat.

Fate

 * The AirEx is part of the storyline set between Nova Prospekt and the City 17 street wars that was completely cut, the game timespan having been reduced to three days instead of the original four. Some elements were however recycled: blowing up the facility to trigger the uprising was merged with the Depot levels to make the Nova Prospekt levels; reaching the top of the industrial tower and blowing up the core of the whole facility was recycled in the Citadel levels, along with the factory-like themes.


 * The AirEx was last worked on in February 2002; the last AirEx map to be modified, the map " " (an overview of the AirEx, with a different design of the reactor) was last modified on that date.


 * It is uncertain whether or not the AirEx exists in the final storyline of the game, but as there are no in-game references to it, it is quite likely that it does not. This is especially true as its effects were to force the remaining humans to wear gas masks apparently constantly, as seen in other related early concepts. The fact that no humans are witnessed wearing said masks means that the idea was almost definitely removed completely.


 * While Alyx and Gordon do not experience a train wreck in Half-Life 2 like originally planned, they do in Episode One and Episode Two.

Trivia
Pistons similar to the ones featured around the AirEx core can be found in maps of the tiles version of the Citadel, although as brushes, not as models.

List of appearances

 * Half-Life 2: Raising the Bar