City 17 Underground

"You're lucky you've got that hazard suit, this water's nasty. Got room for two in there?"

- Alyx Vance

The City 17 Underground is a series of dark underground tunnels, parking lots and storage areas introduced in Episode One.

Overview
Following the Combine invasion and the Seven Hour War, the City 17 underground was apparently no longer used and fell into serious disrepair. However, it is possible that Resistance members used the underground even before the rebellion, as there are numerous bodies to be found, only some of them being recently deceased.

After the destabilization of the Citadel, the underground becomes severely infested with Headcrabs and Zombies, as well as Antlions, who, following the collapse of the Combine's defensive field (previously powered by the Citadel), start establishing a foothold in the city via the tunnels.

Because of the large number of Zombines in the underground, it is possible that the Combine were attacking Resistance members hiding there when Antlions and Xen wildlife were allowed access.

Features
The City 17 Underground mostly consists of underground parking lots, maintenance tunnels, and storage areas. All or most of these facilities are in serious disrepair and many are infested with Zombies and Xen wildlife. There are many storage rooms and lots, as well as sewage pipes. The passageways connecting other areas also contain handwheels to open gates.

Half-Life 2: Episode One
After stabilizing the Citadel long enough to make their escape, Gordon Freeman and Alyx Vance become trapped in the underground after the Razor Train they are riding in derails and crashes. After battling hordes of Zombies, swarms of Antlions, and overcoming various other obstacles, Gordon and Alyx are able to locate an elevator, which they manage to power up and ride to the surface, escaping the hordes of Zombies. Almost arrived to the surface, they have to find a handwheel to unlock the final gate, after which they discover how much more City 17 is ravaged and that Isaac Kleiner took over the Breencast network to deliver vital information to the city's inhabitants.

Behind the scenes



 * This chapter is the first example of Alyx's new co-op features and combat abilities. As she is the only protagonist equipped with a gun, Gordon having only the Gravity Gun (although he originally was to have no weapon at all ), he has to help her killing enemies by aiming his flashlight at them in dark areas, otherwise she does not see them and thus cannot defend herself properly and could get herself killed. He can also throw objects at enemies, but Alyx will always be able to manage all the attacks on her own with a minimum of support from Gordon. She also cannot move in the dark if Gordon disappears with his flashlight turned off, and will call for him helplessly, in a scared tone.


 * This chapter also first introduces the Zombine.


 * In completely dark sections, Zombies will tend to spawn faster if the flashlight is turned off.


 * In completely dark areas where the flashlight is the only source of illumination, the team found that they would often end up with grossly over-exposed views and the HDR parameters were to be modified. In particular, they drastically shrunk the region of the screen where the flashlight's light is located, which is bigger in Half-Life and Episode Two. It permitted them to concentrate only on that area and thus increase the sense of claustrophobia.


 * In that chapter, the player is also forced to block Antlion burrows with cars in a collapsed parking lot, while Alyx helps him fight the Antlion, but without giving him any clues on how to block the burrows.


 * The elevator scene is one of the most tricky parts of the game for the inexperienced player. When Gordon and Alyx arrive at it, its power is down and has to be reactivated through a powerbox located at the other end of a big and completely dark room. When the power is turn on again, Zombies swarm the area, and Alyx and Gordon must bear a huge standoff while waiting for the elevator to come, which obviously take a while, mirroring scenes from previous games such as the teleport scenes at the end of Blue Shift or in the Half-Life 2 chapter Entanglement. The first iteration of this battle was originally very different. The space was larger, had water in it, and was not completely dark. Water is relatively expensive, performance-wise, so the team cut that in favor of more Zombies. They made the level smaller to ensure that the player would see the elevator and recognize the problem that needed to be solved before the fight started. They turned off the lights both to enhance tension and to make this scene a final test of the dark-fighting skills that the player develops over the course of the episode. Finally, they added a wire running along the ceiling from the elevator to the powerbox to give the player a guide as they familiarize themselves with the area.


 * The City 17 vista where Kleiner is seen on the Breencast after reaching the surface is intended to be "an explicit visual reward for surviving the elevator battle."

Trivia
Although Freeman goes through an underground area after Alyx is kidnapped in Half-Life 2, this area is not considered as the same City 17 Underground, the latter consisting more of sewer systems and factory floors.

List of appearances

 * Half-Life 2: Episode One