Half-Life 2: Episode One

Half-Life 2: Episode One is the first of a trilogy of expansion packs/episodes for the 2004 first-person shooter game, Half-Life 2. The episode takes place immediately after the end of Half-Life 2, in and around the war-torn setting of City 17. The player is forced to deal with the effects of their actions during the main game. The episode is a stand-alone game; while a continuation of Half-Life 2, it does not require the original game to be installed or registered to a user's Steam account to play. It takes advantage of several major upgrades to the Source engine since the release of Half-Life 2, primarily its high dynamic range rendering capabilities and the upgraded facial animation system.

Valve views episodes One through Three as tantamount to a stand alone release, essentially Half-Life 3 divided into three episodes. Episode One was released together with Half-Life Deathmatch: Source, a port of the original Half-Life 's multiplayer, which doubles as Episode One 's multiplayer component. The retail copies of Episode One also come with Half-Life 2 Deathmatch for those who have not previously purchased the latter title.

Chapters

 * Chapter 1: Undue Alarm
 * Chapter 2: Direct Intervention
 * Chapter 3: Lowlife
 * Chapter 4: Urban Flight
 * Chapter 5: Exit 17

Events
Following the events of Half-Life 2, Episode One starts out with Gordon experiencing some kind of vision that lets him review 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. As he opens his mouth to say something, he is distracted by blue lights and is separated from Gordon by another group of Vortigaunts. Several of them surround the G-Man and block him off from Gordon with a blue energy shield. He straightens his tie and looks at Gordon while saying in an irritated tone: "We'll see...about that." More Vortigaunts then surround and teleport Gordon, in the same manner as Alyx.



Gordon wakes up outside the Citadel, buried under a pile of rubble. Dog removes these rocks, and Gordon is reunited with Alyx. Alyx contacts Eli Vance and Isaac Kleiner through a monitor, and Kleiner tells Alyx that the Citadel Core is at risk of exploding at any moment. Kleiner states that the explosion could be large enough to level the whole of City 17, and that the only possible way to survive would be to re-enter the Citadel and slow the core's progression toward meltdown. Eli interrupts, showing distress at placing his daughter in further danger, but reluctantly agrees when he sees no other option. Alyx and Gordon re-enter the Citadel to try to reactivate the stabilization mechanism for the core, averting disaster.

During their time in the Citadel, they discover a recording of the discussion between a Combine Advisor and Dr. Breen before Gordon chased him down in Half-Life 2. Breen reprises his words from HL2, saying:


 * "It's me you should be worrying about. I can still deliver Earth, but not without your help... The portal destination is untenable, surely you can set the relay elsewhere. There's no way I can survive in that environment... A host body?! You must be joking! I can't possibly- Oh alright, damn it! If that's what it takes. Just hurry, he's right behind me! Oh shi-"

The recording ends, interrupted by a brief image of a Combine Advisor. Alyx and Gordon are then subject to psychic blasts as an unknown vessel (called Pods in the commentary) containing what looks like a Combine Advisor is transported through a tube in the control room.

Later on, Gordon and Alyx are successful in re-engaging the reactor's containment system, delaying the explosion. Alyx subsequently discovers that the Combine are trying to use the reaction, and therefore the destruction of the Citadel, to send a message to off-world Combine forces. She makes a copy of the message packet to take to Dr. Kleiner and Eli, ensuring that the Combine make them their prime target and even in their disorganized state attempt everything they can to stop them.

Alyx and Gordon then board a Razor Train to escape the Citadel. It becomes apparent that the carriage Gordon and Alyx are in is being used to transport Stalkers. Alyx mourns for the Stalkers and is then interrupted by the train derailing, which wakes the Stalkers. Alyx is trapped under a pod with a restrained Stalker viciously attempting to break loose, relying on Gordon to set her free. After escaping from the train, the duo fights through the rubble of dark, deserted, underground parking garages and tunnels, searching for a way to head up to the surface of the city. In the process, they block off Antlion burrows, and battle various zombies in a pitch black environment, including zombified Combine soldiers (or "Zombines" as Alyx calls them,) which were never seen during Half-Life 2.

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. Dr. Kleiner appears on the screens that Breen used to pass out propaganda, mentioning that the Suppression Field, which had previously prevented human reproduction, is down. As the duo moves on, they engage in several fights with Combine soldiers, Antlions, and zombies.

Alyx and Gordon eventually meet up with Barney Calhoun and a group of other survivors who are preparing to move on a train station in order to escape City 17. With the Combine still following, Gordon and Alyx split up from the group and move through a derelict hospital to draw the remaining Combine forces away from the refugees. Inside the hospital, Combine forces and zombies of all kinds are fighting throughout the collapsing structure, and hastily constructed defences slow Alyx and Gordon down. 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.

After battling Combine soldiers and a Strider, the duo reprogram another train and board the caboose. As the train carries Alyx and Gordon away, the Citadel is visible in the background with the reactor core once again about to explode, and the Combine's message is sent. Several pods similar to the one containing the Combine Advisor in the control room are ejected from the Citadel as it detonates. On two occasions, as pods pass overhead, Gordon and Alyx are hit with psychic blasts. The force of the shockwave from the exploding Citadel causes metal chunks and wreckage to fly toward the train Alyx and Gordon are on as it sends its final transmission, and the screen fades to an ominous white as the shockwave overtakes the train. The last thing that the player hears is the twisting of metal and Alyx whispering Gordon's name. The screen then fades to the credits.

The fate of Alyx and Gordon is continued in the sequel Half-Life 2: Episode Two.

Details
Episode One's focus is on character development, in particular that of Gordon's female sidekick and friend Alyx Vance, to the extent that she accompanies the player for virtually the entire game : "It's kind of ironic that despite so much of the theme of Half-Life 2 being about other characters and other people, you spent most of the game alone," project lead Robin Walker said in the episode's announcement article in PC Gamer UK.

The announcement article also saw Marc Laidlaw explain the game's premise:

"[Episode One] deals with the events and issues set in motion during Half-Life 2. You've done critical damage to the Citadel. The whole place is going to go up, taking out City 17 and what's in its immediate radius. You and Alyx are leading the flight from the city getting up close and personal with some of the creatures and sights from the end of the game."

Despite this comment and much fan speculation, the Combine Crab and Mortar synths were not present in Episode One; Stalkers and previously glimpsed areas of the Citadel are instead encountered and explored by the player.

After some initial confusion, sparked partly with an attempt at humour by PC Gamer UK, which suggested that Alyx was Episode One's playable character, it was confirmed that players would indeed play as Gordon Freeman – unlike the original Half-Life expansion packs, which all dealt with different characters. Part of the reason for this change of direction may lie with the in-house development of Half-Life 2: Episode One: previously, Half-Life expansions were developed by third party Gearbox Software (albeit with scripts produced by Valve).

The game runs on an incrementally upgraded version of Valve's proprietary Source engine, and features both the engine's high dynamic range rendering capabilities, and a new version of its facial animation/expression technology. It also features the commentary node system debuted in the Lost Coast tech demo.

Episode One is available over Valve's Steam platform for $9.95 USD. The game is also being distributed through traditional retail channels by Electronic Arts both as a standalone and as part of the Half-Life 2: Platinum Collection. The game became available for pre-load and pre-purchase through Steam on May 1 2006, with Half-Life Deathmatch: Source and Half-Life 2: Deathmatch immediately available for play as part of the package.

The renaming of Aftermath to Episode One was an indication of Valve's confidence with their episodic structure, an implication confirmed in February and May of 2006, with news of a trilogy of episodes covering the present story arc. While the plots and dialogue of Half-Life and Half-Life 2 were written solely by Valve's in-house writer Marc Laidlaw, the "Half-Life 2 Episodes" are collaboratively written by Laidlaw, Chet Faliszek and Erik Wolpaw with Laidlaw retaining overall leadership of the group.

Allies

 * Dog
 * Alyx Vance
 * Isaac Kleiner
 * Eli Vance
 * Resistance Fighters/Citizens
 * Barney Calhoun

Xenian: Headcrab

 * Headcrab
 * Zombie
 * Zombie Torso
 * Fast Headcrab
 * Fast Zombie
 * Poison Headcrab
 * Poison Zombie
 * Zombine (Overwatch Soldier Zombie)

Xenian: Barnacle

 * Barnacle

Xenian: Antlion

 * Antlion
 * Antlion Guard

Combine

 * Civil Protection
 * Overwatch Soldier
 * Overwatch Sniper
 * Overwatch Elite
 * Stalker
 * City Scanner
 * Manhack
 * Hunter-Chopper
 * APC
 * City Scanner
 * Shield Scanner
 * Combine Gunship
 * Combine Dropship
 * Strider
 * Hunter
 * Combine Advisor

Additional Information and Trivia
With Dr. Breen's absence, Dr. Kleiner has hijacked City 17's public address system, appearing on TV screens throughout the game and keeping the Resistance informed with information on the Combine:
 * All citizens are told to evacuate City 17 as quickly as possible, for while the Citadel's Core is currently stabilized, the Combine will eventually succeed in making it go critical once again, and when that happens, all of City 17 will be destroyed.
 * Humorously, Dr. Kleiner informs humans already out of City 17 that, due to the suppression field being disabled, now would be "an excellent time for procreation", and urges citizens to "do their part for the revival of the species". Alyx replies to this by asking, while glancing at Gordon, "is Dr. Kleiner really telling everyone to... get busy?"
 * The destruction of the Citadel's Dark Fusion Reactor has caused a chain reaction that has put a damper on the entire Citadel Reactor Network, effectively cutting them off completely from the rest of the Combine Empire. However, Dr. Kleiner states that it is only a matter of time before communication is re-established; warning that "In addition to the completely xenotheric species, there are many modified post-human allies (Overwatch Soldiers) still remaining on Earth who will be doing their utmost to re-establish lines of communication and supply with the larger forces."
 * And lastly, Dr. Kleiner hints that the Resistance has made "secret technological advances" that may have long-lasting benefits in the war against the Combine.
 * The group of Vortigaunts in the game's opening scene are part of the "third power" at which Valve hinted ; their role and purpose are mysterious.
 * The G-Man's loss of control to the Vortigaunts is reinforced by his complete absence from the game thereafter. While he appears at least once in most of Half-Life 2's chapters, he is not seen at all in Episode One. Neither, notably, are Vortigaunts, but Combine Advisor(s) is/are seen at several points on various video screens, tracking the player and Alyx from their theft of the Combine's data packet onward. The G-man is also, for the first time ever, without his signature briefcase during the opening scene.
 * This is the first Half-Life game in which Gordon does not start on a train. Somewhat similar scenes are experienced, however, during the slide of the thrown van entering the Citadel and the final train ride out of City 17.
 * A conversation between two resistance soldiers can be overheard in which Dr. Kleiner and other main characters are criticized. One of the soldiers states that he "kind of misses the Combine" and Dr. Breen's show.  The remark "it seems like everyone's a doctor but me" is also made.
 * An often unnoticed addition to the Half-Life series' gameplay made in Episode One is the new change in Combine Soldiers' AI. Episode One makes the soldiers utilize crouching more often than in Half-Life 2, and gives them the ability to crouch while being fired upon in order to "duck" underneath the player's line of fire for the first time in the series. This feature is showcased to the utmost for the first time in the large street battle the player progresses through before entering the rebel safehouse in the game's fourth chapter.
 * By entering the code  and then   into the developer's console, Freeman can use the powerful Blackhole Grenade. To gain further "Blackhole Grenades", the code   can be entered, also providing all the other weapons. These codes require first the use of  . However, this may cause instability to the game and crash the program, especially if the player is sucked into the black hole that has been created.
 * One of the most infamous Achievements in The Orange Box is "The One Free Bullet"; to acquire it, players must complete Episode One having fired exactly one bullet in their entire run-through. This leaves the player using only the Gravity Gun, crowbar, rocket launcher, and grenades.

Critical reception
Critical and public response to Episode One was broadly positive, with some reviewers praising the game for having more intricate, well-paced action than the acclaimed Half-Life 2, though a common critique of the game has been its short length ; depending on the player's skill (or patience) the game can take less time to complete than the company line of 4-6 hours, which has caused various observers to raise the issue of whether it justifies the price tag.

The game's interactivity, particularly in the shape of the character of Alyx, has also received praise.

PC Gamer magazine gave an 85% in the US edition and 90% in the UK edition to the game. In Australia, the magazine PC Powerplay awarded the game with a rarely seen 10/10. Edge gave the game 8 out of 10, praising the "deftness" with which the game was able to direct the player's eyes, and the strength of Alyx as a companion.

Awards

 * IGN: Best PC FPS

Soundtrack
Currently, the songs featured in Half-Life 2: Episode One have been named in a "VLVX_song[number]" format. They are as follows:


 * 1) VLVX_song1 - Self Destruction
 * 2) VLVX_song2 - Combine Advisory
 * 3) VLVX_song4 - Guard Down
 * 4) VLVX_song8 - Darkness at Noon
 * 5) VLVX_song11 - Disrupted Original
 * 6) VLVX_song12 - Eine Kleiner Elevatormuzik (a play on the title of the musical piece Eine Kleine Nachtmusik by Mozart, and also on Muzak music)
 * 7) VLVX_song18 - What Kind of Hospital Is This?
 * 8) VLVX_song19a - Infraradiant
 * 9) VLVX_song19b - Decay Mode
 * 10) VLVX_song21 - Penultimatum