The Stalker transformation process is performed at Nova Prospekt, where Combine scientists sever higher brain functions, experiment on the lobotomized victim in "foul and depraved ways," and embed a number of blackened nano-devices in the skin, "slowly watching the victim lose all humanity." As a result, the appearance and behavior of a Stalker differs significantly from those of a human.
The body of a Stalker is grey, hairless, and heavily emaciated with very little muscle or fat tissue remaining. Its limb extremities, the hands and lower legs, have been amputated and replaced with bolted-on metallic augmentations meant to reduce mobility. All signs of its genitals have been surgically removed, as have its ears and nose. For ease of maintenance and to bring a dependence on the Combine, the Stalker's digestive tract, as well as the majority of organs, has been taken out, resulting in it surviving solely on a saline solution that the Combine provides, further evidenced by the gastric port in their sides. Stalkers also appear to be resistant or immune to radiation, as they are seemingly unaffected even when working near the extremely radioactive Citadel Core.
Stalkers walk slowly in a hunched-over manner with their arms loosely dangling in front of them. When working, they remain mindlessly focused on their tasks. Apparently unable to talk, Stalkers will simply roar and make groans if disturbed. They have small plates on hinges next to their eyes which can apparently be closed during periods of inactivity. Stalkers also have the ability to emit a laser beam using the apparatus mounted on their head. They use this tool to repair Combine devices or in self-defense. This laser is also capable of destroying Energy Balls.
It appears that the Resistance members have full knowledge and understanding of what Stalkers are and how and where they are made. Alyx Vance, seemingly affected by their fate and to some degree reluctant to kill them, explains their origins to Gordon and sympathizes with them. She comments on Nova Prospekt, "It used to be a high-security prison, it's something... much worse than that now." Barney Calhoun also makes the comment, "He was about to board the express to Nova Prospekt!" at the start of the game. Moreover, Resistance members sometimes say, "They're not gonna make a Stalker out of me".
After the cruel transformation process, Stalkers are brought to the Citadel to carry out various menial duties, such as servicing Combine Gunships or maintaining the core and guarding it from intruders. They are transported around while confined in Prisoner Pods, including within Razor Trains called "Stalker cars". Despite being seen in the Citadel, Stalkers are never actually engaged in combat during Half-Life 2. In Half-Life 2: Episode One, however, it is possible, and sometimes required, to engage in combat with them in order to more easily achieve mission objectives, as their lasers prevent certain tasks from being completed. Stalkers largely ignore the presence of Alyx and Gordon, only becoming aggressive and attacking when deliberately provoked or another individual is killed in front of them. As stated by Alyx, Stalkers "shouldn't bother us if we leave them alone."
The first appearance of a Stalker occurs in Nova Prospekt, where it can be seen via a monitor. None can, however, be directly observed until the chapter Our Benefactors, in which multiple Stalkers performing their duties or being transported in Prisoner Pods are encountered during Gordon's journey in his own Pod through the Citadel.
Half-Life 2: Episode One
Episode One is where the exact nature of Stalkers is first revealed, as they can be seen up close. They are first encountered after Gordon and Alyx enter the Citadel and come across a Force Field being held active by a Stalker at a terminal. Reprogramming a Rollermine and making it hostile to all Combine units, thereby eliminating the Stalker, allows the duo to proceed. Stalkers are then notably encountered near the Citadel Core where they utilize their lasers to hinder Gordon's progress by destroying energy orbs holding powered bridges active.
In order to make their escape from the Citadel, Gordon and Alyx enter a Razor Train that happens to be carrying dormant Stalkers immobilized inside their Pods. When it crashes, some of them are killed, while others begin to shriek and twitch. One of the caskets occupied by a screaming Stalker pins Alyx to the side of the wreck, which causes her great emotional distress.
|Half-Life 2: Episode One|
|Contain the Citadel core without killing any Stalkers.|
Behind the scenes
According to Ted Backman, the enemy's designer, the Stalker was inspired by a black version of the Half-Life Skeleton multiplayer model. The developer who created and featured it in his levels proposed that a "black skeletal character that can hide in dark shadows and leap out at you as you got close" be included in Half-Life 2. The horror aspects of this concept were then further developed.
- “The Stalker idea came from wanting something that crept around in the shadows and then lunged at you. We took a half-baked idea and turned it into something more horrific because the Stalkers are really the victims. When you face them, they are these crazed half-human things that you can't help but almost pity. I was hoping to put enough humanity into the things that it wasn't just a scary monster. Instead it was something that presented a moral dilemma every time you had to deal with it, which I think is a more interesting problem. It is more horrific to have to deal with an insane hostage than something that just wants to eat your brains.”
- — Ted Backman
Marc Laidlaw expanded on the enemy's origins, remarking that Stalkers were one of the earliest creatures put into Half-Life 2, and the developers tried them in several gameplay environments. Initially, they were foes that crouched down in the dark and followed players from behind, surprising them when they turned around. While Valve had numerous gameplay concepts for them, such as Stalkers being used in puzzles where they could cut through sheet metal with their beams, they ultimately didn't end up being fun. As these sequences were "scripted and stagey," they decided to aim for an emotional impact instead and make Stalkers an important story element.
The first known in-game iteration of the Stalker, found in the Half-Life 2 leak, was based directly on the concept art featured in Half-Life 2: Raising the Bar. Captions included in the image provide some in-universe backstory to this cut design. Appearing even more skeleton-like than in the final version, the Stalker can be seen wearing not only a blinder but also a muzzle through which it is able to lap up fluids; both devices are said to have been installed for ease of control and handling. In addition to having portions of its forearms and lower legs severed, the human captive is hobbled during the conditioning process to further prevent escape attempts. Once it is ready to serve, braces that allow for walking are fixed to the stumps. This design was then expanded upon, equipping the Stalker with tools attached to each of its arms, resulting in the final iteration included in the Half-Life 2 leak.
Stalkers were originally planned to be featured frequently as hostiles throughout Half-Life 2, being notably fought in the Air Exchange, on the Borealis, and in City 17, among other locations. Stalkers were apparently being transported on the Borealis, one being found inside a hanging cage. A large group of them were also intended to be encountered in Kraken Base where they assisted Elena Mossman in running the underwater research base. The combat elements were ultimately cut and, later, re-introduced in Episode One. In the Half-Life 2 leak, Stalkers are much more agile, have melee attacks, a more damaging laser, and emit wilder shrieks and babbling when active.
On August 16, 2016, the source files of a Stalker model that appears to be earlier than the one found in the leak were publicly leaked. It is slightly taller and doesn't include the arm-attached tools. Of note are previously unseen animations, notably
s_runpause2 which convey a much more cowering personality.
Older model, released as part of the 2016-2017 leak, also lacking its tools.
Kraken Base cabal possibly featuring Stalkers held inside tubes.
Stalker inside the early Depot.
Stalker running past Odell on the Borealis.
Stalker firing its laser on City 17's rooftops.
Texture in the Half-Life 2 leak files used for the WC map pack maps
Stalker being supervised by a Combine Soldier in the Citadel.
List of appearances
- Half-Life 2: Raising the Bar, page 79
- The Orange Box Prima Guide, page 34
- Half-Life 2: Raising the Bar (uncorrected proof), page 261
- Looking Back... Half-Life 2: Episode One on Computer And Video Games (October 12, 2006) (archived)
- Half-Life 2: Raising the Bar, page 78
- Half-Life 2 leak
- Marc Laidlaw Vault on ValveTime.net forums (December 20, 2012)
- Half-Life 2 Cut Content on Facepunch (April 17, 2016)
- Half-Life 2 Cut Content on Facepunch (August 16, 2016)