Half Life 2 Episode One 5.3
Stepping into the hazard suit of Dr. Gordon Freeman, you face the immediate repercussions of your actions in City 17 and the Citadel. Rejoin Alyx Vance and her robot, Dog, to once again aid the human resistance in their desperate battle against the totalitarian alien menace of the Combine.
Episode One is the first in a planned trilogy of adventures that extends the award-winning and best-selling Half-Life adventure. New Source Engine technology was introduced in Episode One to support advanced artificial intelligence, new levels of graphics and character interaction.