Dark Energy

Dark Energy is the thirteenth and final chapter of Half-life 2.

Dark Energy takes place at the tip of the Citadel spire, housing both Dr. Breen's office and the Citadel's Dark Fusion Reactor. It details the close of Gordon Freeman's effort against the Overwatch, bringing him face to face with the Combine's human liaison, Wallace Breen, and ultimately to a showdown within the reactor itself, in which the scientist-come-resistance fighter delivers a crippling blow to the structure, launching a devastating series of events.

The Liaison:

Gordon Freeman arrives at the summit encased within a pod. He is greeted by two Combine Elites who quickly disarm him of his Super Gravity Gun. The treacherous Judith Mossman appears to escort him herself, in which she apologies – sincerely – for what she has done. Inside the office, Dr. Breen is interrogating Eli Vance and describing to him the 'world beyond our own'. He cuts off on seeing Freeman and delves into what can only described as a victory speech, wherein he claims he can “Dictate the terms of any bargain I care to make with the Combine.”

Mossman interjects, citing the preservation of Eli as critical to their research efforts. Breen, as though he's heard it a hundred or so times before, simply shakes his head and accuses of not doing what's right for the good of mankind. Eli, furious, asks Breen to tell him what he'd be saving them from, and, shaking off a direct answer, the Administrator summons Alyx Vance, who is also captive, in an attempt to sway Eli's allegiances.

After failing at this Breen threatens to send them to the far-side of a Combine portal, snidely intoning “Oh, it's hardly the worst, but you might find that hard to believe once you get there.” He quickly turns his attention to Freeman, and drops a tantalizing hint about his services being up for grabs to "the highest bidder", prompting an enraged response from the captive Vances.

At this critical moment and finally seeing the ruthlessness in which Breen choses to deal with his so-called 'old friend', Judith Mossman intervenes and turns on her former master. Breen flees and she liberates the captives, consoling Eli as Gordon and Alyx give pursuit.

Dark Fusion Reactor:

Alyx thanks Gordon for his help, and as the elevator rises they catch a snippet of what appears to be a one-sided conversation. Breen is arguing furiously with something, demanding safe passage off of Earth, and then rejecting the idea of a 'host body' to do so. As the elevator stops Gordon and Alyx catch a glimpse of a large, slug-like creature on the monitor. It stares at them curiously for a moment, and then disappears as Breen flees to the adjacent elevator and makes good his escape.

Alyx turns her attention to the Combine control panel and removes the metal shields protecting the view screen to reveal the tip of the teleport reactor. Unable to shut it down, she tells Gordon he has to go into the reactor and stop Breen if he can. Once inside Gordon finds Breen preparing for his ascension to the reactor spire. Breen smugly begins trivializing Freeman's efforts and belittling him as he pursues him to the summit.

Eventually Freeman reaches the top as the portal opens, revealing a terrifying vista of another universe with a nebula-like sky and several beacons surrounding what appears to be a massive teleport site. As Gordon begins tearing apart the reactor Breen, worried and not so self-assured, pleads with him to stop: “You don't know what you'll unleash! You could bring down this whole Citadel! Think man, think of the people below!”.

But it's too late. The portal closes, Breen descends and Alyx Vance is ecstatic. Unfortunately the reactor begins to detonate, and a cascade of volatile energy spews from the damaged portal. Time slows to a stop, and a familiar, sinister voice calls out to its pawn.

“Time, Dr. Freeman. Is it really that time again?”

The G-man appears, and having altered Gordon's perception of time congratulates him on his success and informs him of the many offers he has received for his employment, and that whilst he normally would not consider these, they are “extraordinary times.”

Leaving Alyx Vance at the tip of the erupting spire, he returns his pawn to the timeless stasis, to wonder for the fate of his friends.

Trivia

• Dark Energy consists of the map d3_breen_01.