Portal 2

Portal 2
Portal 2 retail cover art, featuring co-op campaign characters Atlas (bottom) and P-Body (top).
Developer(s)	Valve Corporation
Publisher(s)	Valve Corporation
Director(s)	Joshua Weier
Producer(s)	Gabe Newell
Artist(s)	Jeremy Bennett Randy Lundeen (art directors)
Writer(s)	Erik Wolpaw Jay Pinkerton Chet Faliszek
Composer(s)	Mike Morasky Jonathan Coulton (Ending Theme: "Want You Gone") The National ("Exile, Vilify")
Series	Portal
Engine	Source (Build 4710, 6 October 2011)
Platform(s)	Microsoft Windows Mac OS X PlayStation 3 Xbox 360
Release	'Retail'Steam (Worldwide) April 19, 2011
Genre(s)	Puzzle-platform game
Mode(s)	Single-player, co-operative multiplayer

Portal 2 is a first-person puzzle-platform video game developed and published by Valve Corporation. It is the sequel to Portal (2007) and was released on April 18, 2011 for Microsoft Windows, Mac OS X, PlayStation 3, and Xbox 360. The retail versions of the game are distributed by Electronic Arts, while digital distribution of the Windows and OS X versions is handled by Valve's content delivery service, Steam. Portal 2 was announced on March 5, 2010, following a week-long alternate reality game based on new patches to the original game. The sequel's release on Steam was preceded by a second multi-week alternate reality game, the Potato Sack, involving 13 independently-developed titles which culminated in a distributed computing spoof to release Portal 2 several hours early.

Like its predecessor, Portal 2 primarily comprises a series of puzzles that must be solved by teleporting the player's character and simple objects using the "portal gun", a device that can create inter-spatial portals between two flat planes. The game's modified physics engine allows momentum to be retained through these portals, which must be used creatively to maneuver through the game's challenges. In addition to retaining most of the original Portal's gameplay elements, the sequel added new features, including tractor beams, laser redirection, bridges made of light, and paint-like gels that give surfaces special properties (e.g. accelerating the player's speed, allowing them to jump higher). These gels were created by the team from the Independent Games Festival-winning DigiPen student project Tag: The Power of Paint.

Within the single-player campaign, the player returns as the human Chell, having awakened from stasis after many years. Chell must navigate the now-dilapidated Aperture Science Enrichment Center with the portal gun while the facility is rebuilt by the reactivated GLaDOS, an artificially-intelligent computer that appeared in Portal as its main antagonist. The storyline is longer than that of Portal's, and introduced new characters, including: Wheatley, a personality core voiced by Stephen Merchant; and recordings of Cave Johnson, the deceased CEO of Aperture Science voiced by J. K. Simmons. Ellen McLain reprised the role of GLaDOS. Jonathan Coulton and The National produced one song each for the game. Portal 2 also includes a two-player co-operative mode, in which the robotic player-characters Atlas and P-Body are each given a portal gun and are required to work together to solve test chambers specifically designed to require co-operation. Valve provided post-release support for the game, including additional downloadable content and a simplified map editor to allow players to create and share test chambers with others.

Though many reviewers were initially concerned about the difficulty of expanding Portal into a full sequel, critics universally praised Portal 2. The game's writing, pacing, and dark humor were highlighted as stand-out elements, with critics applauding the voice work of McLain, Merchant, and Simmons. Reviews also highlighted the new gameplay elements, the game's challenging but surmountable learning curve, and the additional co-operative mode. Numerous gaming journalists ranked Portal 2 among the top games of 2011, including several naming it their Game of the Year.

Gameplay

Like its predecessor, Portal 2 challenges players to use portals to traverse rooms in unusual manners. A player-character executing the "flinging" maneuver gains speed by falling into the blue portal to shoot across a wide gap upon exiting the orange portal.

Portal 2 is a puzzle game presented from the first-person perspective. Players act as Chell in the single-player campaign, as one of two robots, Atlas and P-Body, in the co-operative campaign, or as a simplistic humanoid icon for community-developed puzzles. All four can move, look, and interact with the environment. The character can withstand damage for a brief period but will die under sustained injury. There is no penalty for falling onto a solid surface, even at high speed, but falling into bottomless pits or pools of toxic liquid kills the player-character immediately. When Chell dies in the single-player game, the game restarts from a recent checkpoint; in the co-op game, the robot respawns shortly afterwards without restarting the puzzle. The goal of both campaigns is to maneuver the character(s) through the Aperture Science facility. While most of the game takes place in modular "test chambers" with clearly-defined entrances and exits, other parts occur in behind-the-scenes areas where the objectives are less clear.

The initial levels provide a tutorial on general movement controls and how to interact with the environment. Afterwards, the player is required to solve puzzles using the "portal gun", formally the Aperture Science Handheld Portal Device, which can create two portals connecting two distant surfaces. Only some surfaces can accept portals; these are depicted as matte white, continuous, and flat. As in Portal, characters can use these portals to move unconventionally between rooms, or to "fling" objects or themselves across a distance. Unlike in Portal, outlines of placed portals are visible through walls and other obstacles for easy location.

New game elements include Thermal Discouragement Beams (lasers replacing the energy balls from Portal), Excursion Funnels (tractor beams), and Hard Light Bridges, all of which can be transmitted through portals. The new Aerial Faith Plates launch the player or objects through the air, and sometimes into portals. The turrets from Portal return, and players must disable them or avoid their line of sight. The Weighted Storage Cube has been redesigned, and there are new types: Redirection Cubes, which have prismatic lenses that redirect laser beams, and spherical Edgeless Safety Cubes, which made a brief appearance in one of Portal's advanced chambers. The heart-decorated Weighted Companion Cube reappears briefly. Early demonstrations included Pneumatic Diversity Vents, shown to transport objects and transfer suction power through portals, but these do not appear in the final game because the technology was not ready in time. All of these game elements either open locked doors, or aid or hamper the character from physically reaching the exit.

Portal 2 also introduces paint-like gels that impart certain properties to a surface or object coated with them. Gels are dispensed from pipes and can be transported through portals. Orange Propulsion Gel boosts the player's speed as they cross a surface, blue Repulsion Gel allows them to bounce from a surface, and white Conversion Gel allows many surfaces to accept portals. Some surfaces, such as grilles, cannot be coated with a gel. Water can block or wash away gels, returning the surface or object to its normal state.

The game includes a two-player co-operative mode in addition to the single-player mode. Two players can play at the same console with a split screen, or at their own computers or consoles; Microsoft Windows, Mac OS X, and PlayStation 3 users can play with each other regardless of platform. Both player-characters are robots who control separate portal guns and can use the other character's portals as necessary. Each player's portals are of a different color scheme, one in blue and purple and the other in orange and red, to distinguish between the two sets. An initial "calibration" chamber separates the characters to teach the players to use the communication tools and portals. Most later chambers are less structured and require players to use both sets of portals for laser or funnel redirection, launches, and other maneuvers. The game provides voice communication between players, and online players have the ability to temporarily enter a split-screen view to help coordinate actions. Players can "ping" to draw the other player's attention to walls or objects, start countdown timers for synchronized actions, and perform joint "gestures" such as waving or hugging. The game tracks which chambers each player has completed and allows players to replay chambers they have completed with new partners.

According to Valve, each of the two campaigns (single-player and co-operative) is 2 to 2.5 times as long as the campaign in Portal, with the overall game five times as long. Erik Wolpaw, Portal 2's lead writer, estimates each campaign is about six hours long. Portal 2 contains in-game commentary from the game developers, writers, and artists, as in previous Valve games. The commentary, accessible after completing the game once, appears on node icons scattered through the chambers.

Plot

Portal 2 follows the player-character Chell after the end of Portal, in which she destroys the rogue artificial intelligence construct GLaDOS that ran the Aperture Science Enrichment Center where the game is set. In Portal's backstory, Aperture Science conducted experiments to determine whether human subjects could navigate dubiously safe "test chambers", until GLaDOS killed the scientists with a neurotoxin. The ending of the first game, retroactively patched just prior to the sequel's official announcement, shows Chell being dragged away from the remains of GLaDOS by an unseen figure with a robotic voice, later identified by writer Erik Wolpaw as the "Party Escort Bot." A promotional comic shows that an estranged Aperture Science employee placed Chell into suspended animation for an indefinite amount of time, in an effort to save her life.

The Portal series shares a universe with the Half-Life series. Portal takes place between Half-Life and Half-Life 2, and Portal 2 is set "a long time after" its predecessor (presumably years later).

Single-player campaign

Chell wakes to find herself in a stasis chamber modeled after a motel room. An announcer's voice guides her through a cognitive test before she is put back to sleep. When she awakens again, many years have passed, and the Aperture Science facility has become dilapidated and overgrown. Wheatley (Stephen Merchant), a personality core, moves the room—located in one of hundreds of shipping containers in a giant warehouse—and the pair attempt to escape via the test chambers. In the process, they discover the dormant GLaDOS (Ellen McLain) and accidentally reactivate her. GLaDOS, who has not forgiven Chell for "murdering her years ago", separates Chell from Wheatley and begins rebuilding the facility.

Potatoes are a recurring motif of Portal 2. Wheatley traps GLaDOS's core personality in a potato battery while he takes over the Aperture Science facility.

GLaDOS begins testing Chell in a series of new test chambers, until Wheatley helps Chell escape. The pair disable the neurotoxin and turret manufacturing plants before confronting GLaDOS a second time. Chell performs a "core transfer", replacing GLaDOS with Wheatley in the body that controls the facility. He becomes intoxicated with power, and places GLaDOS's personality into a module powered by a potato battery. GLaDOS convinces Wheatley that Chell believes she was the only one that worked towards their escape, leading to Wheatley sending both Chell and GLaDOS into an abandoned area of the facility miles underground. As they fall, GLaDOS chastises Chell for putting Wheatley in "her body", claiming that he was designed to be "the dumbest moron who ever lived", producing illogical thoughts to hamper GLaDOS's decision-making processes in an attempt to make her less dangerous.

After they have landed deep underground, GLaDOS is abducted by a bird, while Chell explores the decommissioned section of the facility where she finds herself. From there, she ascends through a series of old test chambers in chronological order (with the decor slowly changing from 1950's styles to ones more similar to the style seen early in the story and in the first Portal game). As she navigates the chambers, she regularly receives audio recordings of Aperture Science's CEO, Cave Johnson (J. K. Simmons). The player learns that Johnson became increasingly embittered and deranged as his company lost money and prestige, leading to him being fatally poisoned by moon dust (which, coincidentally, is a "great portal conductor"). His assistant, Caroline (McLain), became a test subject for a mind-to-computer transfer experiment, ultimately becoming part of GLaDOS. Chell reunites with GLaDOS, forming a partnership to stop Wheatley before his incompetence destroys the complex, while GLaDOS struggles with the revelation about Caroline.

Chell and GLaDOS return to the modern facility and face Wheatley, who is driven by GLaDOS's body to continue to test them. In a final "surprise", Wheatley tricks Chell into a series of death traps. Chell escapes due to Wheatley's clumsiness and lack of logical thinking, and makes her way to his chamber. In their final confrontation, Chell attaches three corrupt personality cores (Nolan North) to the body that Wheatley inhabits, allowing GLaDOS to initiate a second core transfer and put herself back in control. However, just as Chell is about to conclude the core transfer, Wheatley reveals that he has booby-trapped the process. With the facility's reactor on the brink of meltdown, the roof collapses, revealing the night sky. Chell shoots a portal at the moon overhead, causing the vacuum of space to pull her and Wheatley through the other portal still inside the chamber. GLaDOS pulls Chell back inside, where she falls unconscious, leaving Wheatley stranded in space, along with a corrupt, space-obsessed personality core.

When Chell awakens, GLaDOS explains that she learned valuable lessons about humanity from her Caroline persona. She promptly deletes this aspect of her personality, reverting to her usual antagonistic attitude. She finally allows Chell to leave the facility, explaining that trying to kill Chell has proven so difficult that she has chosen to just let her go. The game ends as Chell is taken to the surface and, after a brief interlude, exits into a wheat field from a corrugated metal shed. The charred and battered Weighted Companion Cube (supposedly incinerated during the events of Portal) is then flung out the door after her before it slams shut. In the epilogue, Wheatley floats helplessly through space and expresses regrets about betraying Chell.

Co-operative campaign

The co-operative story takes place after the single-player campaign and has some ties into it, but players do not necessarily need to play them in that order. Player characters Atlas and P-Body are bipedal robots, each with a fully functioning portal gun, who navigate five sets of test chambers together. The robots are introduced in the singleplayer campaign as replacements for GLaDOS's human test subjects. After completing a test chamber, the robots are disassembled and reassembled at the next chamber. After completing each set of chambers, they are returned to a central hub. The puzzles in each set of chambers focus on a particular testing element or puzzle-solving technique. In the first four sets, GLaDOS prepares the robots to venture outside of the test systems of Aperture Laboratories to recover data disks. She destroys them and restores their memories to new bodies, similar to what happens when they die from a test chamber hazard. At first, GLaDOS is excited about her non-human test subjects, but later becomes dissatisfied because the two robots can't actually die. At the conclusion of the co-op story, the robots discover and gain entry to "the Vault", where humans are stored in cryostasis. GLaDOS gleefully congratulates the robots on locating the humans, whom she sees as new test subjects. She then violently disassembles the robots, telling them, "We still have a lot of work to do."

Development

After the success of Portal, which was originally an add-on product to the game compilation The Orange Box, Valve decided to make Portal 2 its own product. Work began almost immediately after the release of Portal. They committed more resources than for the first game; Portal had a team of seven or eight people, but Portal 2 had a team of 30 or 40. The initial team of four expanded as subgroups formed to devise game mechanics and plot the story. Participants in internal review processes were inspired to join the project by what they saw. According to Erik Wolpaw, some Portal 2 developers worked on the Left 4 Dead games to help them meet milestones, but then returned to Portal 2, "with extra people in tow." Kim Swift, Portal's designer, left Valve for Airtight Games halfway through Portal 2's development.

Project manager Erik Johnson said Valve's goal for Portal 2 was to find a way to "re-surprise" players, which he considered a "pretty terrifying" prospect. In March 2011, one month before the game's release, Valve president Gabe Newell called Portal 2 "the best game we've ever done."

After Portal 2's release Geoff Keighley reported that, according to Newell, "Portal 2 will probably be Valve's last game with an isolated single-player experience". Keighley later stated that the use of the word "probably" suggests that "this could change." Newell said that Valve is not "giving up on single-player at all", but intends to include more social features on top of the single player experience, akin to the co-operative mode in Portal 2.

Design

Initially, the development team planned to drop the portals from Portal 2. For five months Valve focused on a new gameplay mechanic called F-Stop, the specifics of which are not yet known outside of Valve, because the team considered using it for a new game. Though the new mechanics prompted some positive feedback, every playtester expressed disappointment at the omission of portals. Following a report in Kotaku of some leaked aspects of the game's plot then under consideration, Newell directed the team to reconsider its plans for Portal 2, including the lack of portals.

Several of the early test chambers in Portal 2 reused the original chambers from Portal; deterioration and aging were added to provide familiarity to the player while suggesting the length of time between the two games.

Johnson stated that Valve's aim was not to make Portal 2 more difficult than its predecessor, but instead to produce "a game where you think your way through particular parts of the level, and feel really smart when you solve it." Portal 2 gives the player incremental steps in understanding game mechanics, an approach that led to two basic types of test chambers. The first type, which Valve calls "checklisting", provides a relatively safe environment for the player to experiment with a new gameplay concept; the second type combines elements in new ways to force the player to think laterally, producing challenging and rewarding puzzles. Chambers were first developed through whiteboard via isometric drawings. The developers performed a sanity check on the chamber before crafting simple levels with the Hammer level editor. Extensive play-testing ensured the solutions to each chamber were neither too obvious nor difficult, as well to observe alternative solutions discovered by playtesters. Based on its input, the design team would either keep these alternative solutions viable or block them if they were too easy. Once a chamber was considered ready, artists would add elements such as detailed texturing, dynamic lighting, and vegetation, for rendering within an advanced version of the Source game engine. These versions would then be sent back for further play-testing to verify the new elements did not prevent players from finding solutions, with further iterations between artists and playtesters until such issues were resolved. Some previous elements from Portal were modified to better suit Portal 2, where most players would already be familiar with the game mechanics but still required some learning curve for novice players and new elements. One example is the replacement of energy spheres used in the first game, which the player would need to observe their movement to understand how they interact with the test chambers, with lasers which provided immediate feedback of this nature and reducing the learning curve time.

Several of Portal 2's early chambers were built by applying decay, collapse, and overgrowth to Portal chambers. This was done to give Portal players a sense of nostalgia and a sense of how much time had passed in the game world. It also let the team replace the less resolved textures from the first game with higher-resolution, dirty textures the newer engine could support. The middle section of the single-player campaign takes place in larger in-game spaces, where the developers made most surfaces unable to accept portals, to force players to find creative ways to cross them. In the final section, when Wheatley controls the Aperture facility, "the level designers just had a blast" creating deranged chambers reflecting Wheatley's stupidity, according to writer Jay Pinkerton. The designers recognized that solving puzzles would tire players mentally, so they inserted occasional "experiences" to give the player a rest and advance the plot.

Portal 2 features gels that impart special properties to surfaces or objects they coat. Here, blue Repulsion Gel causes the painted turrets to bounce off any surface.

Portal 2 integrates a game mechanic from Tag Team's Tag: The Power of Paint: paint-like gels that impart special properties to surfaces or objects they coat. Impressed by Tag, Valve hired its creators to develop the mechanic further and only later decided to include it in Portal 2; however, Valve's vice president of marketing says that "the decision to combine their tech with Portal 2 came naturally". Journalists have likened Tag to Narbacular Drop, the DigiPen student project that became Portal. The Repulsion (jumping) and Propulsion (running) gels in Portal 2 are original to Tag. Using the third Tag gel, which allows the character to walk on any coated surface regardless of gravity, caused motion sickness in playtesters. It was replaced by Conversion gel, which integrates with the portal mechanic. The gels give the player more control over the environment, which increased the challenge for the puzzle designers. The gels are rendered using fluid dynamics routines specially developed at Valve by the former Tag Team.

In addition to the gels, Portal 2 uses advanced rendering techniques for liquid pools, developed for Left 4 Dead 2. Portal 2 combines "flowing" surface maps to mimic the motion of water with "debris flow" maps and random noise to create realistic real-time rendering of water effects.

The co-operative gameplay came about from requests from players as well from anecdotes of players working together on the same computer or console to solve the game's puzzles, likened by Wolpaw to players working together on the same computer to solve point-and-click adventure games. The co-operative campaign was also inspired by Valve's Left 4 Dead co-operative games, where players would enjoy discussing their personal experiences with the game when they were done playing. While the single player campaign in Portal 2 is designed to avoid frustrating the player, the co-operative levels are focused on coordination and communication, and are recognized by Valve as being much more difficult than the single-player puzzles. Valve avoided including timed puzzles into the single-player experience in Portal and Portal 2, but found that their inclusion into the co-operative mode was effective, as it gives players a positive feeling after they successfully plan and execute difficult maneuvers. Each puzzle chamber in the co-operative mode requires four portals to solve it; this is to prevent puzzles being solved by the actions of only one player. As soon as a playtester discovered a way to complete a puzzle with one set of portals, the level was sent back to the drawing board for further work. Except in a few cases, the chambers were designed so that both players would remain in sight of each other in order to promote communication and co-operation. Some of the puzzle chambers were designed as asymmetric chambers, where one player would manipulate portals and controls to allow the other player to cross the room. This helped emphasize that the two characters, while working together, are also separate entities. The ability to tag surfaces with instructional icons for one's partner was soon realized as a necessary element, as it was found to be much more effective for co-operation than simple verbal instruction.

In addition to the co-operative mode, Valve considered a competitive mode. According to Wolpaw, the mode resembled a variation of speedball, where one team would attempt to transport a ball from one side of the playing field to the other using portals, while the other team would attempt to stop them with their own use of portals. Wolpaw said the matches would commence with this objective in mind, but quickly descend into chaos. They realized people enjoyed solving puzzles with portals more and therefore focused on the co-operative mode.

Writing

Writers Jay Pinkerton (left), Erik Wolpaw, and Chet Faliszek at the 2012 Game Developers Conference receiving the "Best Narrative" award for Portal 2

Erik Wolpaw returned to write the game's script, along with National Lampoon veteran Jay Pinkerton and Left 4 Dead writer Chet Faliszek. Wolpaw and Pinkerton wrote the single-player campaign story, while Faliszek developed GLaDOS's lines for the co-operative campaign. There are 13,000 lines of dialogue in the single player and co-operative campaigns combined. While the writers felt they needed to create a larger story for a stand-alone title, they wanted the game to "feel relatively intimate", and avoided adding too many new characters. The writers considered expanding on the "sterility and dryness" from Portal, while injecting more comedy. Wolpaw noted that while some developers have been moving towards art games, no one had made a comedic video game. The game's story was developed in tight coordination with the gameplay development and testing.

Portal 2 was originally envisioned as a prequel to Portal, to be set in the 1950s, long before GLaDOS's takeover of the Aperture Science facility, with events set in motion when Aperture CEO Cave Johnson becomes trapped within a computer. Johnson would have eventually led an army of robots against the player to rise to power within Aperture. In June 2008, based on information from a casting call website and leaked script samples, Kotaku reported that Valve was seeking voice actors for Johnson, naming him as an AI and identifying the game as a prequel. Valve attributed this leak to an "overeager agent". Following negative playtester feedback to the omission of Chell and GLaDOS, Portal 2 was re-conceived as a sequel. The team returned to the idea of exploring parts of the facility from Aperture's early days, and reincorporated Johnson through a series of recordings.

Originally, the writers had conceived of several "joke" premature endings to the game if the player performed certain actions, similar to the mid-point of Portal where GLaDOS' actions to incinerate Chell imply finality to the game. One example ending included shooting a portal onto the surface of the moon and then dying from asphyxiation over a closing song, but these were considered to require too much development effort for little payback and were scrapped. They did reuse the idea of shooting a portal on the moon as part of the game's final ending. They also scrapped an ending where Chell would utter a single word, but felt it wasn't as humorous as they desired. The co-operative campaign was originally going to feature a much-more detailed storyline, in which GLaDOS would send the robot pair to discover human artifacts, such as comic based on a Garfield pastiche, hoping to use it to make the robots more human-like for purposes of testing. The writers recognized that unlike the captive audience of the single-player campaign, the two players in co-operative mode may simply talk over the story, and thus the story was trimmed to very basic elements.

Wolpaw commented that while many story elements of Portal are revisited in Portal 2, he avoided some of the memes—such as the frequently-repeated "the cake is a lie"—stating that "if you thought you were sick of the memes, I was sick of it way ahead of you". However, Wolpaw "couldn't resist putting in just one" cake joke. The writers did not attempt to predict or write new memes, believing that "you can't really plan for [dialogue to become a meme] because if you do it probably seems weird and forced". Nevertheless, the sequel did produce its own memes, including the space-obsessed personality core.

Richard McCormick of PlayStation 3 Magazine has identified several elements of Portal 2's story relating to the mythological tale of Prometheus, with GLaDOS personified as Prometheus as granting knowledge—in the form of the portal gun— to humanity and then being punished by being bound to a rock, pecked at by birds, and cast into the pits of Tartarus, and Wheatley as his foolish brother Epimetheus. Within the game, a sentry gun makes reference to the Prometheus mythology, the word "Tartarus" can be seen in the supporting columns in the depths of Aperture Science, and one portrait of Cave and Caroline also shows Aeschylus, the presumed author of Prometheus Bound. Journalists and players have also found connections between Portal 2 and Half-Life 2. In a crossover, Portal 2 suggests that an experiment accidentally teleported Aperture Science's cargo ship, the Borealis, into the seemingly impossible position in which was discovered at the end of Half-Life 2: Episode Two.

Character design

Stephen Merchant (top) voices Wheatley, the personality core, while J. K. Simmons (bottom) voices Cave Johnson, the eccentric CEO of Aperture Science.

See also: Development of Chell, GLaDOS, Wheatley, and Cave Johnson

Though Portal 2 introduced some new characters, the writers wanted to maintain the one-on-one relationship between each character and the player-character. Wolpaw observed that the game actually has three endings, one for each of the main characters: GLaDOS learns a lesson but then chooses to delete it; Wheatley learns a lesson and longs to apologize for it; and Chell escapes into an unknown world possibly controlled by the Combine, the brutal transhuman empire from Half-Life 2.

Valve explored introducing a new protagonist for Portal 2. Though playtesters accepted playing as a different character for the first part of the game, they became disoriented when GLaDOS did not recognize them. Ultimately the writers returned to Chell, the protagonist of Portal. Valve artists explored different outfits for Chell, and considered changing her (ambiguous) nationality. Ultimately they returned to the orange "dehumanizing" jumpsuit from Portal, now with the top tied around Chell's waist to enhance freedom of movement and help her "stand out more as an individual". PSM3 called the new look "controversially sexy". As in the first game, Chell's facial appearance is based on that of voice actress Alésia Glidewell. Chell continues her role as a silent observer, as the straight man in response to the insanity around her and as a way to refuse to give her antagonists any satisfaction.

GLaDOS, the primary antagonist in Portal, returns as a major character, with Ellen McLain again as voice actor. As part of her overall character arc, the plot moves GLaDOS from a state of anger with Chell for her actions in Portal, which Wolpaw believed "was going to get old pretty quick", to an internal struggle.

The writers considered introducing about six personality cores stored in portable spheres, whose main function would be story advancement. They planned cores based on Morgan Freeman's character Red from The Shawshank Redemption and Quint from Jaws, among others. Ultimately they decided to concentrate on a single core, Wheatley, recycling two of the rejected cores in the final boss fight. Wheatley is voiced by Stephen Merchant; early demonstrations at trade shows used the voice of Valve animator Richard Lord. The writers wrote Wheatley's lines with Merchant in mind, citing his unique "vocal silhouette" and his ability to ad lib in a "frantic" manner. They initially assumed Merchant would be unavailable and contacted The IT Crowd's writer Graham Linehan to try to get Richard Ayoade, but then discovered Merchant was interested. Merchant spent around sixteen hours recording lines and was given freedom to improvise. Karen Prell led the animation team for Wheatley and the other personality cores.

J. K. Simmons voices Cave Johnson, Aperture Science's founder and CEO. Simmons's selection helped to solidify the character's development. Pictures of Johnson, based on the face of lead animator Bill Fletcher, appear throughout Portal 2. Though comparisons have been made between Johnson and Andrew Ryan, the wealthy industrialist that created the fictional underwater city of Rapture in BioShock, Wolpaw says they did not consider this character while creating Johnson. The writers required another character to play off Johnson, but did not want to hire another voice actor. Having already enlisted McLain to play GLaDOS, they had her voice Johnson's assistant, Caroline. The reuse of McLain's voice led to the creation of a backstory and subplot about GLaDOS's creation. This element was also directed by the writers having a "true moment of incredible panic" when they realized that their plans to have Chell and GLaDOS play off each other like in a buddy cop film would only work if both partners spoke. To remedy this, the creation of the Caroline subplot gave GLaDOS an external situation to deal with and to drive the story during the middle act of the game.

The co-operative campaign contains a separate story involving the two robotic characters and GLaDOS. Initial plans called for Chell and a new human character, "Mel", with dialogue for GLaDOS playing off their "image issues" that was retained after the switch to robots. GLaDOS seems troubled by the robots' cooperation, and attempts to aggravate their relationship through verbal trickery, such as praising one robot over the other. Valve initially considered having GLaDOS deliver separate lines to each player, but they found this to be a significant effort for minimal benefit. The writers also tried adding lines for GLaDOS that would make the players compete against each other for rewards such as meaningless points, but playtesters did not respond well. Faliszek noted that in co-operative games, it can be difficult to deliver key dialogue or in-game events to players, who may not be looking in the right direction at the right time. Instead, using lessons learned from Left 4 Dead, Faliszek and Wolpaw kept the story and key comedic lines short, and repeated them frequently.

The two robotic characters were originally more human and less robotic, similar to designs seen in the movie Westworld. The final designs are a modified personality core and a turret gun with haphazardly attached limbs. The numerous deaths players would endure throughout the game would be rather gruesome with human or human-like characters, but the deaths of robotic characters provide comical animations, such as struggling while being crushed by a lowering ceiling. The artists felt the look of the robots would help tell the story, and the fact that they are holding hands emphasizes the co-operative mode. "Expressive noises" are used in place of distinguishable dialogue, and mannerisms were designed to be a double act, similar to Laurel and Hardy. The robots' voices were provided by voice actor Dee Baker, who had done similar robot voices for the various Star Wars: The Clone Wars media.

The writers saw Aperture Science itself as a character. It is depicted as a "living, breathing place", and "a science company that's gone mad with science." In the Lab Rat comic, the facility is described as a "beautiful and terrible" place, "a metastasized amalgam of add-ons, additions and appropriations. Building itself out of itself."

Music

Main article: Music of Portal 2

Portal 2 contains both scored and procedurally generated music created by Valve's composer, Mike Morasky. The game also includes two songs; "Want You Gone" recorded by Jonathan Coulton, used as the final credits song for the single player mode, and "Exile Vilify" by the band The National, used in the background of one of the Rat Man's dens. The full soundtrack "Songs to Test By", containing most of the songs in the game, was released as a free download across three volumes between May and September 2011.

Release

Announcement

A montage of about 20 images, each showing a good deal of static and noise over the images included. The images are of everyday office items, in some cases, a set of 4 images together to mark specific letters or numbers.

The alternate reality game that led up to Portal 2's announcement included decoding SSTV images embedded in an update to Portal.

In January 2008 Valve spokesman Doug Lombardi told Eurogamer, "There'll be more Portal, for sure." Portal designer Kim Swift confirmed work on Portal 2 the next month. Swift said multiplayer Portal was possible "from a technology standpoint" but would be "less fun than you'd think."

Portal 2 was officially announced on March 5, 2010. Events during the preceding week foreshadowed the announcement. On March 1 Valve released a patch for Portal that included a new achievement, "Transmission Received", requiring the player to manipulate in-game radios. This revealed new sound effects that became part of an alternate reality game (ARG). The effects included Morse code strings that suggested GLaDOS was rebooting and SSTV images from a grainy Aperture Science video. The images included hints to a BBS phone number that, when accessed, provided a large number of ASCII-based images relating to Portal and segments of fictional Aperture Science documents. Many of these ASCII pictures were later published in Game Informer. New ASCII images continued to appear on the BBS after the official announcement. Background on the ARG is embedded in additional SSTV images found in a hidden room in Portal 2. According to these, the ARG had a budget of US$100 and was designed to attract casual players, who would find radios in Portal, and more enthusiastic players, through the decoding and deciphering. The BBS connected to a PC in a Valve employee's kitchen; the Valve office phone lines were too modern to support a BBS.

Gabe Newell and the GLaDOS blue screen of death at the 2010 Game Developers Conference.

A second Portal patch on March 3 altered the game's ending sequence. Gaming journalists speculated that an announcement of Portal 2 was imminent. On March 5 Game Informer unveiled the cover of its April issue; Portal 2 was officially launched.

During the week following Portal 2's announcement, Gabe Newell's speech accepting the Pioneer Award at the Game Developers Conference 2010 ended with a fake blue screen of death appearing on a screen behind him. The message purported to be from GLaDOS and hinted of further Portal 2 news at the upcoming E3 2010. Two weeks before the E3, game journalists received a cryptic e-mail, worded as a press release from Aperture Science, hinting that the presentation on Portal 2 would be replaced with "a surprise" jointly hosted by Aperture Science and Valve. This prompted speculation that the surprise would be the announcement of Half-Life 2: Episode Three, but Valve confirmed that it would be about Portal 2. The surprise was the announcement of Portal 2 on PlayStation 3.

Portal 2: Lab Rat

An early chamber in Portal 2 which includes art drawn by Michael Avon Oeming and Andrea Wickland as the in-game Rat Man character. The artwork depicts the events of the first game and ties in with the "Lab Rat" comic.

To help develop the fictional history of Aperture Science, Valve created a digital comic to tell the story of the "Rat Man", a schizophrenic who is unseen in the games themselves but creates murals and scrawlings that guide Chell in both games. The comic, "Portal 2: Lab Rat", takes place both during and after Portal, explaining the events that led to Portal 2. The Rat Man's artwork appears early in Portal 2, where it retells the plot of Portal. Michael Avon Oeming, who had worked on comics for Valve games Team Fortress 2 and Left 4 Dead, and Valve in-house artist Andrea Wicklund drew the comic. Ted Kosmatka wrote most of the story with input from the Portal 2 writers. The 27-page comic was made available online in two parts about two weeks before the game's release and was also bundled with the game itself. Dark Horse Comics has published "Portal 2: Lab Rat" in a printed anthology of Valve comics, Valve Presents: The Sacrifice and Other Steam-Powered Stories, in November 2011.

In the comic Doug "The Rat" Rattmann, is a scientist working in the Aperture facility. He escapes GLaDOS's initial neurotoxin attack, but suffers symptoms as his schizophrenia medication runs out, including hallucinating his talking Weighted Companion Cube. Noticing that Chell is uniquely tenacious among the test subjects held by Aperture, Rattmann moves her to the top of the queue of testing subjects, thus starting the events of the first Portal. After Chell defeats GLaDOS, Rattmann escapes Aperture but returns against the Companion Cube's objections when he sees the Party Escort Bot dragging an unconscious Chell back inside and into a disabled cryo chamber. He ensures that Chell is kept in indefinite suspended animation, but he is shot by a turret in the process. He then enters a stasis pod himself, and what becomes of him afterward is unknown.

The Final Hours of Portal 2

The Final Hours of Portal 2 is a digital book written and created by Geoff Keighley. This digital book gives insight on the creation of Portal 2. Keighley had previously worked as an editor at GameSpot, writing several 10,000-word "Final Hours" pieces on various games where he visited the studios during the late development phases to document the creation of the game. One piece, "The Final Hours of Half-Life 2", allowed Keighley to interact with Valve during 2003 and 2004 and talk with the staff as they completed work on Half-Life 2. Keighley wanted to recreate a similar work for Portal 2, with focus on making it an interactive work for the iPad. Keighley was granted "fly on the wall" access to Valve when Portal 2 was being produced. The initial iPad release was written by Keighley with work by Joe Zeff Design, a studio that had also produced digital applications for Time magazine. The interactive work provides movie clips and short applications to demonstrate the various mechanics of the game and stages of the game's development. The work was later ported into an non-interactive eBook, and into a application with the same iPad interactivity on the Steam platform. With the iPad and Steam version, Keighley is able to offer live updates to the work; upon release of the "Peer Review" downloadable content pack, the work was updated with an additional chapter discussing the creation of the new content and what new features players could expect in the future from Portal 2.

Marketing and release

The March 2010 announcement called for Portal 2 to be released in late 2010. In August 2010 Valve announced that the game's release had been moved to February 2011, with a Steam release date of February 9. This was to complete changes to the game's dialogue, to fill and connect the sixty-some test chambers already created, and to finish refinements to the gel gameplay mechanic. Valve announced a further delay in November 2010, setting the week of April 18, 2011, for worldwide release through retail and online channels. Wolpaw stated that this delay of eight weeks at the end of the project was used to expand the content of the game before reaching an internal milestone called a "content lock", where no further content could be added. The remaining development work involved debugging. Newell allowed the delay, given the added benefits of the new content, because he felt there would not be the loss of any commercial opportunities as a result. On February 18, 2011, Newell confirmed that Valve had completed the development work on Portal 2 and that they were "waiting for final approvals and to get the discs manufactured".

Portal 2 was the first Valve product simultaneously released for Windows and Mac OS X computers through the Steam platform. Retail copies for all platforms are distributed by Electronic Arts.

Valve created their own series of television commercials to promote Portal 2. Valve had worked with advertising agencies in the past, but Lombardi found the advertisements created had shown little ingenuity; Lombardi's frustrations included "Copycat treatments. Cliché treatments. Treatments that reveal the agency wasn't listening in the initial meeting." Using viewer feedback, Valve tailored the ad content until they were satisfied with the results. The ads took eight weeks to complete. Valve also developed additional online promotional videos, featuring J. K. Simmons narrating as Cave Johnson, to promote new elements of Portal 2's gameplay. These videos were part of a larger effort described by Newell as a "documentary-style investment opportunity" for Portal 2. An earlier video release on February 14, 2011, promoted the co-operative aspect of Portal 2 as an ideal Valentine's gift. The video "lit up our preorders, our buzz, all the metrics that are used and collected by publishers and retailers". Lombardi felt the videos "dwarfed the demos and interviews we did". Valve also offered Portal 2-themed merchandise, such as posters, drinking glasses, and t-shirts, including one that parodies the Three Wolf Moon shirt.

Portal 2's release was preceded by another alternate reality game, called the Potato Sack, which includes thirteen independently-developed games. Envisioned by Newell around December 2010, the developers were brought to Valve to discuss and plan the "Cross Game Design Event", to culminate with the early release of Portal 2 on Steam. The developers were given access to Valve's art and audio assets to incorporate Portal-themed content into their games. The game was launched on April 1, 2011, with a Steam bundle sale of these titles. Players worked to solve the multi-tiered puzzle, coordinating efforts through web sites and chat rooms, which some journalists believed pointed to the release of Portal 2 on April 15, 2011, instead of the target release date of April 19, 2011. Eventually, on April 15, the players discovered "GLaDOS@Home", a distributed computing spoof that encouraged participants to play the various games to unlock Portal 2 earlier. As a result of these coordinated efforts, the game was unlocked about ten hours early.

The game includes bonus content, primarily four promotional videos and the Lab Rat comic. It also includes an interactive trailer for the 2011 film Super 8, constructed with the Source game engine. A feature called "Robot Enrichment" allows players to customize the co-op campaign characters with new gestures or cosmetic items such as hats or flags. These can be earned in-game, traded with other players, or bought through microtransactions at the in-game store.

Downloadable content

File:Valve hammer editor.jpg
File:Portal map editor.jpg

While existing tools like the detailed Valve Hammer Editor (top) can be used to develop Portal 2 puzzles, Valve has released a highly simplified version that is accessible to all users to construct their own levels.

Valve planned to produce downloadable content for Portal 2, with the first content, "Peer Review", released on October 4, 2011. The content, which is free for all users regardless of platform, includes a new co-op campaign which loosely extends the game's story where, after a week from the end of the co-operative campaign, GLaDOS prepares Atlas and P-Body to deal with an intruder within Aperture Science—the bird that had previously abducted her as a potato. The content also adds a "challenge mode" similar to that which appeared in the first Portal—players attempt to complete specific chambers with the shortest time or fewest number of portals used, both which are tracked on overall and friends leaderboards. The challenge modes are available for both single player and co-operative modes.

According to Faliszek, user-generated content for Portal 2 will be available on all platforms through various delivery methods, but the necessary modding tools will only be available for Windows due to software dependencies. Valve released beta versions of the modding tools on May 10, 2011. Valve helped to back a contest held by the community mapping site, "Thinking with Portals" in May 2011, providing prizes for the top-selected maps. A free title update for the Microsoft Windows and Mac OS X version, the "Perpetual Testing Initiative", was released on May 8, 2012, and includes a new level editor and a means of sharing and obtaining new user-created levels through the Steam Workshop. Previously, Keighley reported that Valve has been working on the highly-simplified level editing tools, "a Photoshop for test chambers", to allow novice editors to assemble test chambers without learning how to use the modified Valve Hammer Editor, as well as an in-game system via the Steam Workshop to deliver user-created levels to players. This mapping system entered beta testing around March 2012. Within a few days of release, the Perpetual Testing Initiative add-on had seen over 35,000 user-created maps, with 1.3 million downloads of these maps through Steam.

Valve also continues to support fan reuse of Portal 2 content, offering selected assets and aid. The Microsoft Windows release of the independently-developed game, Bastion includes a weapon inspired by Portal 2's Conversion Gel and turrets; its developer, Supergiant Games, received some writing assistance from Eric Wolpaw and new lines for the turrets voiced by McLain. Similarly, the Steam release of the game Dungeon Defenders includes pre-order content based on the portal gun from Portal and various Team Fortress 2 items. An add-on scenario for Hidden Path Entertainment's tower defense game Defense Grid: The Awakening, entitled Defense Grid: You Monster, incorporates GLaDOS as an antagonist within the game using new dialog from McLain and assets from Portal 2. Wolpaw and McLain also helped to create additional lines spoken by GLaDOS for a custom single player map commissioned by Gary Hudston, which he used to propose marriage to his fiancee, Stephanie. For release of a patch for Bethesda's The Elder Scrolls V: Skyrim that incorporated support for Steam Workshop content, Valve developed a free add-on module that introduced the Space Core as a non-player character that would follow players around the Skyrim world.

Hardware support

PlayStation 3

The announcement that Portal 2 would be available on PlayStation 3 came as a surprise, because Gabe Newell had criticized that console in the past citing difficulties in the port of The Orange Box. The move toward the PlayStation 3 was a result of growing frustration with Microsoft's policies for Xbox 360 content, including the difficulty of pushing patching and new content to players. Newell saw Sony's publication model as more open, allowing for Steam-like features on the console side.

Portal 2 is the first game on the PlayStation 3 to support a subset of features from Steamworks, including auto-updates, downloadable content, and community support. The game supports cross-platform play between the PlayStation 3 and the Windows and Mac OS X versions. On the PlayStation 3, the Steam overlay shows the player's friends on both Steam and the PlayStation Network, with achievements rewarded for both Steam and PlayStation Network trophies. PlayStation 3 players can unlock the game on Steam for Windows and Mac OS X for no additional charge. The integration of Steamworks on the PlayStation 3 allows Valve to collect data about problems that arise after shipping and push appropriate updates. Valve has stated they do not plan on integrating other PlayStation 3 features, such as 3D television or PlayStation Move support.

Valve has said that, despite additional support for PlayStation 3 over Xbox 360, the "core game" is the same across both platforms.

Razer Hydra

Valve developed a version of Portal 2 native to the Razer Hydra motion controller for PC that allows enhanced control of some game elements. Ten additional single-player levels are available as downloadable content for this version. Writer Chet Faliszek said Razer developers spent nine months to a year in-house at Valve preparing the native version. A limited edition of the Razer Hydra comes bundled with a copy of Portal 2 for PC.

Reception

Pre-release

A crowd gathering for the Portal 2 demonstration booth at the PAX Prime 2010

Portal 2 was a strong favorite of gaming journalists during closed-door previews at the E3 2010 convention. The Game Critics Awards, selected by a large number of journalists and critics, awarded Portal 2 the title of Best PC Game and Best Action/Adventure Game, and nominated the game for Best of Show and Best Console Game. IGN named Portal 2 as its Best of E3 for PC, Xbox 360, and PlayStation 3 systems as well as Best Puzzle Game, and nominated the game as Best Overall Game. Gamespy named Portal 2 the Best Overall Game and Best Puzzle Game of E3. Portal 2 won the 2010 Spike Video Game Award for "Most Anticipated Game for 2011".

Reception

Aggregate scores

Aggregator	Score
GameRankings	(PC) 95.03% (X360) 94.54% (PS3) 93.78%
Metacritic	95/100

Review scores

Publication	Score
1Up.com	A+
Edge	9/10
Eurogamer	10/10
Famitsu	37 (10/9/9/9)
G4	5/5
Game Informer	9.5/10
GameSpot	9.0/10
IGN	9.5/10
PC Gamer (US)	94/100

Post-release

Portal 2 received universal acclaim from reviewers on its release, resulting in an average score of 95 out of 100 according to review aggregator Metacritic, and, between the different platform versions, was ranked as the 3rd through 5th highest rated game by the aggregator through 2011. Several reviewers identified Portal 2 as an early contender for "Game of the Year", while others called it one of the best games of all time. Prior to its launch, several critics had expressed concern that Valve might be unable to take the shorter, experimental, Portal from The Orange Box and make it into a full retail game, but upon release the game was widely considered to be as good as or better than the original. Eurogamer's Oli Welsh said that the game was able to avoid the normal pitfalls that developers introduce in sequels, stating that "Portal is perfect. Portal 2 is not. It's something better than that." Gus Mastrapa of the A.V. Club commented that with Portal 2, Valve had alleviated any doubts that "Portal could be expanded into a big, narrative experience with all the bells and whistles of a mainstream gaming hit". IGN's Charles Onyett considered that the sequel "makes the original look like the prototype it was" by expanding the game in gameplay and story.

Most reviewers praised the writing and voice acting in the game. Entertainment Weekly's Dan Stapleton of PC Gamer was able to predict many of the plot twists within Portal 2's story but "still looked forward to witnessing exactly how the characters would react"; he praised the development of the characters, as "their charm makes what would otherwise be an empty and lifeless world feel boisterous and alive". The individual characters were well-received. Oynett believed that Merchant's "obvious enthusiasm for the role benefits the game" and that the "consistently clever writing perfectly complements the onscreen action". Game Informer's Adam Biessener considered Johnson to be an even better character than GLaDOS, a tribute to "pitch-perfect delivery" from Simmons with "brilliant comedic timing". In contrast, Peter Bright of Ars Technica commented that, compared to the loneliness and despair he felt while playing the first game, the additional characters, specifically Wheatley and GLaDOS, lost some of this feeling and "the inane babble served only to disrupt the mood".

Portal 2's additional gameplay elements, like light bridges, lasers, and the gels, were praised as appropriate additions to the game. Furthermore, the reviewers were pleased with the level of difficulty of the puzzles throughout the game, appearing visually complicated at first but with uncomplicated solutions. Narcaisse had stated that he feared the addition of the new gameplay elements would "dilute the purity of the experience", but instead was pleased with the results as "everything's still executed with Valve's high level of charm and panache". Tom Hoggins of The Telegraph praised the manner which with these elements were introduced through a "brilliant learning curve of direction, rather than instruction", and considered it a "design ethos that is supremely generous, but dealt with marvellous economy". Kohler considered that the game's puzzles "never require excessively complicated solutions", and that much of the puzzle solving is "filled with moments that will have you slapping your forehead". Stapleton was not as pleased with the gel additions as with the other new mechanics, calling it "difficult to control". He felt that they have "only a couple of uses at most". Bright felt that Portal 2 was easier than its predecessor, in part that he felt much of the game was effectively tutorials for the new gameplay additions, requiring "careful use of the tools provided", leaving him with the impression that "the game was on rails".

The co-operative puzzle solving aspect was highlighted as a valuable addition to the game. Welsh called the co-operative mode "one of the most satisfying and genuinely collaborative gaming experiences you can have with a friend". Onyett praised Valve for using the lessons they learned from Left 4 Dead to build the co-operative mode that requires "a game design that doesn't simply encourage but requires you to work together". Several reviewers praised the non-verbal cues that players could initiate to work with their partners.

Portal 2 was praised for its detail in design, sound, and music. Nelson credited the "sheer amount of detail" put into the game's world, and felt it was "very real and natural with brief moments where you're simply sucked into this world". Onyett was impressed with the amount of visual details and capabilities Valve achieved from their Source game engine and that the added details and animations of the levels "consistently serv[ed] not only to entertain the eye but to expand our understanding of the game's characters". Hoggins believed that the game's world reacted to the player "in a startlingly organic way", and praised Valve's design as "an achievement of world-building that compares favourably with BioShock's underwater city of Rapture". Some reviewers did note that the second act of the game, taking place in the less-structured portion of the old Aperture facilities, while filled with impressive vistas, may be confusing to some players. Young believed in this section the game "cranks up the difficulty level at a speed that may dishearten casual gamers", and recounted several difficulties, including having "absolutely no idea where I was supposed to head next". Kohler further considered that, while the player would explore the abandoned areas of Aperture, there is very little to do in these areas, and called them "a lot of sterile, duplicated, non-interactive environments".

Watters noted that the loading time between the game's levels, in contrast to earlier Valve games, are "long enough to make you take notice and wish they were shorter". Watters also commented on the lack of challenge chambers or other advanced features packaged with the shipped product that were present in the original, though that Portal 2 is "not light on content" without these. Welsh noted that the attempt to recapture the spirit of the song "Still Alive" in the end credits of Portal 2 "was a mistake".

Journalists noted that many of the initial user reviews for Portal 2 on Metacritic evoked a negative opinion of the game. These users cited complaints about the game being too short (with some saying it is only four hours long), the existence of paid downloadable content at launch for some versions, and supposed evidence that the game on Microsoft Windows and Mac OS X were ports of the console version. Journalists have defended Valve in these claims, countering concerning the game's length and the game content, and suggesting that the quality of the graphics on the Windows and Mac version did not suggest a simple console port. Some journalists also identify that the minimal impact of The Potato Sack alternative reality game on the early release of Portal 2 may be influencing the user scores.

Awards

Portal 2 has won the title of "Ultimate Game of the Year" at the 2011 Golden Joystick Awards, and ranked second place on Time's "Top 10 Video Games of 2011". Gamasutra, IGN, Eurogamer, Kotaku, the Associated Press, and The Mirror listed Portal 2 as its top video game of 2011. The game received twelve nominations including "Game of the Year" for the 2011 Spike Video Game Awards, the most of any title, and won for "Best PC Game", "Best Male Performance" (for Stephen Merchant), "Best Female Performance" (for Ellen McLain), "Best Downloadable Content", and "Best Multiplayer Game". The title was nominated for five Game Developers Choice Awards for 2011, including "Game of the Year", and ended up winning in the "Best Narrative", "Best Audio" and "Best Game Design" categories. The game was nominated for ten Interactive Achievement Awards, including "Game of the Year", from the Academy of Interactive Arts & Sciences, and ultimately won for "Outstanding Achievement in Connectivity", "Outstanding Achievement in Original Music Composition", and "Outstanding Character Performance" for Wheatley. Portal 2 was nominated for six BAFTA video game award categories, and won for "Best Game", "Best Story" and "Best Design". The Game Audio Network Guild awarded the game for "Best Dialog", "Best Interactive Score", and "Best Original Vocal - Pop" (for "Want You Gone"). In the inaugural New York Videogame Critics Circle Awards, Portal 2 was given the top honors for best writing and best acting.

Sales

Based on sales data from Amazon.com, Portal 2 was the best-selling game in the United States in the first week of its release. It fell behind others, including Mortal Kombat, in its second week. According to NPD Group, Portal 2 was the second-best selling game in the U.S. in April 2011, at 637,000 copies, and the fourth-best selling in May. However, NPD does not include sales on Valve's Steam platform.

Portal 2 was the best selling game in the United Kingdom in the week of its release, the first time a Valve game had placed first. It retained the top spot during its second week.

Portal 2 was released days before the PlayStation Network outage. Gamasutra analyst Matt Matthews concluded, based on NPD Group data, that the outage "did not seriously affect retail sales of software", but some developers did report drops in sales. ShopToNews analyst Joe Anderson expected that the effect of the outage on UK sales of Portal 2 would be mild.

On June 22, Newell announced that Portal 2 had sold 3 million copies. As of late July 2011, Electronic Arts has stated that more than 2 million copies of Portal 2 at retail have been sold worldwide. In an August 2011 interview, Newell stated that "Portal 2 did better on the PC than it did on the consoles". Upon release of the Perpetual Testing Initiative in May 2012, Newell stated that Portal 2 had shipped more than 4 million units, with the personal computer versions outselling the console versions; overall, both Portal and Portal 2 had shipped more than 8 million units.

External links

• "Think With Portals" - Official website
• Portal 2 at IMDb
• Valve Corporation
• Eric Wolpaw Portal 2 presentation as part of the New York University Game Design Series, May 6, 2011
• "The Final Hours of Portal 2" Digital book by Geoff Keighley