Dog

"The first model was about yay high. I've been adding to him ever since."

- Alyx Vance

Dog (occasionally written as DØg or dØg after the writing on his body) is Alyx's "pet" robot. Dr. Eli Vance built Dog to protect his daughter, Alyx, when she was young. Dog was originally a relatively small, 1 meter (three feet) robot. As Alyx grew older, she began upgrading the robot by adding additional parts, and it now towers 2.5 meters (eight feet) high.

Half-Life 2


Gordon Freeman is first introduced to Dog in the Black Mesa East scrapyard. As a part of a tutorial on operation of the Gravity Gun, Alyx arranges a game of "fetch" between Gordon and Dog, using an inert Combine rollermine as the ball. The game is interrupted by a Combine assault on Black Mesa East. After heading back inside, Dog opens the passage to an unused tunnel leading towards Ravenholm for Gordon to help him escape. While Gordon enters the tunnel, Dog stays behind to help Alyx and others defend the lab.

Gordon meets Dog again after he and Alyx teleport from Nova Prospekt to Doctor Isaac Kleiner's lab at the end of the chapter Entanglement. The company splits again – when Gordon and Dog set off to find Barney Calhoun; Alyx however stays with Dr. Kleiner who refuses to leave without his pet headcrab, Lamarr. As Anticitizen One begins, Dog is quick to leave Gordon behind and charge at a nearby group of Combine troops outside the lab, tossing a ruined car at them and even fighting off an APC. He then tears apart a gate for Gordon, allowing him to proceed. However, Dog goes berserk immediately after and jumps aboard a Combine Dropship, departing into the unknown. It is worth noting that this whole scene – unlike other sequences where supporting characters fight alongside Gordon – is entirely scripted, and as such requires no involvement from the player at all.

Dog eventually manages to find Barney, and Gordon meets both of them in the square toward the end of the chapter "Follow Freeman!" in a scene where Dog, in the heat of the battle, knocks over a large statue of a horse. As Barney reports to the player, Dog is probably aware of the fact that Alyx is already in the Citadel, and so tries to reunite with her, being completely uncontrollable by others. The last time Dog is seen in Half-Life 2 is when he, once again, opens a passage for Gordon – this time allowing him to enter the Citadel by lifting a heavy piece of a Mobile Wall, uncovering an ancient aqueduct.

Half-Life 2: Episode One


The game opens with Gordon under a pile of rubble from which Dog lifts him out of. Dog then proceeds to aid Alyx and Gordon in first contacting Eli Vance and Isaac Kleiner (by using his body as an antenna), and then resolving the issue of entering the Citadel by throwing Alyx and Gordon across a dividing ravine in a burnt-out van. Dog is told by Alyx to return to her father, and is not seen again for the rest of the game.

Half-Life 2: Episode Two
In Episode Two, Dog appears late in the game and fights a Strider, with little regard for his own well-being. After narrowly avoiding being crushed multiple times, he manages to tear off the casing of the Strider's control mechanism and subsequently shuts it down by removing its "brain". Afterward, he challenges the player to a race. If the player is able to beat Dog, Alyx will remark "Better luck next time, slow poke." However, if Dog wins, he will dance around triumphantly. Soon after, Dog is left outside to help patrol White Forest while Gordon and Alyx continue on to meet Eli and Kleiner.

Towards the end of the episode, Dog appears once again, but is distracted by something in the distance. During his absence, Eli, Gordon, and Alyx are ambushed by Combine Advisors and Eli is shortly thereafter killed. Before the Advisors manage to repeat the horrific process on Gordon and Alyx, Dog shows up narrowly saving them. He manages to injure one Advisor considerably, whilst the other flees from his attacks relatively unscathed. As Eli dies in Alyx's arms, Dog leans over, watching in sorrow.

Personality and skills
Dog, much like a real dog, is very friendly, loyal, and has an intelligent personality. Like Barney Calhoun, Dog provides the player with bits of comic relief. If the player looks at it while it is idle, it may perform a dance. Dog makes friendly and playful noises such as beeps and whines, as well as less-friendly roars when provoked. Dog's body is constructed largely of scrap metal, hydraulics, and wires, with what appears to be a scrapped City Scanner for a head, though it has three flaps while scanners normally have four, but it does have one extra link where the fourth flap should go.

Dog has a Zero Point Energy device, much like the Gravity Gun, built into one hand, to pick up and throw things. Dog has amazing strength, and proves extremely useful through the course of the story, as he can throw large objects (such as vehicles) at enemies or pry open areas which are otherwise inaccessible to Gordon. Dog appears to be completely invulnerable to any damage used in-game; it never takes apparent damage from any source including weapons, fire, or explosions. However, this is untrue; he simply has a huge amount of health to make sure he does not die in-game (as opposed to using very fast regeneration of health, as Alyx does). It is possible for him to die, but this can only be observed if the player spawns him using the console in a combat situation that he would not normally be involved in.

Dog seems to have a sixth sense, being able to determine where Alyx is, even when she was inside the Citadel. He is able to sense when Alyx is in danger, for instance, when he rushed to the site where the Dropship crashed in Episode Two.

Behind the scenes



 * Dog does not have any combat AI, and all in-game scenes with Dog fighting are scripted. If a spawned Dog is approached by anything threatening, even a common headcrab, the spawned Dog will flee. If no enemies are present, he will find a nearby small object and throw it at the player.


 * Dog's character, even though important to the story, also plays a recognizable role for the game. His battle sequences are often humorously exaggerated, where the player can see him throw large objects great distances to wipe out entire squads of Combine soldiers, or furiously attack disoriented and panicking groups of enemies without caring for consequences nor taking any noticeable damage, whether it is crushing a handful of soldiers or taking a dropship head-on.


 * Valve commented on the Half-Life 2: Episode One commentary that players love Dog, so they made him the first thing the player sees at the start of the episode.


 * Dog was one of the few Half-Life 2 concepts that went from the first sketch straight into the game with relatively few changes to the design. Designers were inspired by classic movie robots, as Dog is a near cousin to Robbie from Forbidden Planet.


 * Early texture sheets from the playable Half-Life 2 Beta show that Dog was to feature other colors, such as aqua blue, maroon, pink or green.

Trivia

 * Dog's right foot may have been based on that of the Combine Guard's.


 * The aggressive roars that Dog makes when provoked are very similar to the same noises that Striders make.


 * Animations of The Tank from Left 4 Dead (another Valve game released in 2008) may have been based on that of Dog.

List of appearances

 * Half-Life 2
 * Half-Life 2: Raising the Bar
 * Half-Life 2: Episode One
 * Half-Life 2: Episode Two