Dr. Gordon Freeman is the main protagonist of the Half-Life series. He is a theoretical physicist who is forced to defend himself and the Human race against hostile Aliens and other enemies following an experiment gone wrong. In the process, he becomes an almost legendary resistance hero, eventually becoming one of the leaders of an uprising against the alien invaders.
In Half-Life, players assume the role of the protagonist, Dr. Gordon Freeman, a recent MIT graduate in theoretical physics, and also a recent employee at Black Mesa. After an experiment that goes horribly awry when an unexpected Resonance Cascade (an apparently completely fictitious occurrence) rips dimensional seams that devastate the facility, Gordon must fight to escape the now alien-infested facility as creatures from another world — known as Xen — subsequently enter in ever-increasing numbers through these dimensional seams.
Alyx Vance is the deuteragonist of Half-Life 2 and its Episodes. She is portrayed as a woman in her mid-twenties, and is a prominent figure in the Resistance campaign against the rule of the Combine.
Taking place in and around City 17, nearly two decades[2] after the events of the first game, Half-Life 2 follows the scientist Gordon Freeman as he is thrust into an unfamiliar environment in which the aftermath of the Black Mesa Incident has come to bear fully upon human society. Freeman is forced to battle against increasingly unfavorable odds in order to free Mankind from the Combine. In his struggle, he is joined by various allies, including fellow scientists, rebels, and friends (such as Alyx Vance) - all shocked to see him alive.
Dog is a robot, built by Eli Vance to protect his daughter Alyx when she was a child. Dog's original model was around one meter in height, but as Alyx grew older, she began adding upgrades and new parts to Dog, and he towers around 2.5 meters tall at the time of Half-Life 2.
The episode takes place immediately after the end of Half-Life 2, in and around the war-torn setting of City 17. The player is forced to deal with the effects of their actions during the main game. The episode is a stand-alone game; while a continuation of Half-Life 2, it does not require the original game to be installed or registered to a user's Steam account to play. It takes advantage of several major upgrades to the Source engine since the release of Half-Life 2, primarily its high dynamic range rendering capabilities and the upgraded facial animation system.
The G-Man is a mysterious and enigmatic character encountered several times in the Half-Life series. Referred to as a "sinister interdimensional bureaucrat",[3] he is known to display peculiar behavior and to wield powers far beyond those of a human. His identity and motives remain completely unexplained.
Continuing with Valve's method of orienting each episode around a particular theme or set of technologies, Episode Two focuses on expansive environments, travel, and large, nonlinear battles. Following the closing events of Episode One, it sees Gordon Freeman and the series' other major characters moving away from City 17 to the surrounding wilderness.