Though the add-on's length is shorter than the campaign found in Half-Life 2, offering an estimated four to six hours of play, the narrative addresses lingering questions and fleshes out the storylines of the principal characters in greater detail.
The expansion pack also focuses on freedom fighter Alyx Vance and her robotic companion, Dog, as they team up with Freeman to defeat the oppressive alien race known as the Combine. Gordon Freeman to engage in more alien and mutant battles from within the decaying walls of City 17. Players slip on the battered spectacles of Dr. Half-Life 2: Episode One continues the single-player story from the critically acclaimed Half-Life 2.
