In this final chapter, Gordon helps evacuate citizens and rebels and fights a strider blocking the train tracks. The Citadel blows at the end of the chapter, and its shockwave overtakes Alyx and Gordon’s train.

Upon reuniting with Barney at the train station, Alyx and Gordon work to move the citizens to the trains while facing increasing Combine opposition. They then decide to stay behind to lure the Combine away from Barney and the citizens as they board the train and make their escape.

In this lengthy chapter, Gordon and Alyx work their way through the city streets and a dangerous hospital before meeting up with Barney to make their way to another train station so they may finally escape.

Eventually, the duo manages to find the exit of an underground train station and Gordon and Alyx come up to the surface, observing the citadel from afar, and the destruction already visited on City 17.

This chapter sees Gordon and Alyx fleeing through the city’s ruined, dark, and zombie-infested City 17 Underground as they continue to flee the city.

Alyx is trapped under a Combine Prisoner Pod with a restrained Stalker viciously attempting to break loose, relying on Gordon to set her free.

Following the events of Half-Life 2, Episode One starts out with Gordon experiencing some kind of vision or flashback that shows the explosion of the Citadel’s Dark Fusion Reactor. As time stops, several purple glowing Vortigaunts appear and rescue Alyx Vance. The G-Man is then seen walking through the door made of light toward Gordon Freeman.