Half-Life 2: Episode One PC FAQs, walkthroughs, and guides

The player reprises his role of Dr. Gordon Freeman, who must immediately face
the repercussions of his actions in City 17 and the Citadel. Freeman reconnects
with Alyx Vance and her robot, Dog, as they continue their support of the
resistance's battle against the Combine forces.

The intense, real-time gameplay delivered in Half-Life 2: Aftermath is made
possible only by Source, Valve's proprietary engine technology which has been
enhanced with new rendering technology and advanced artificial intelligence to
deliver new levels of graphics and character interaction.