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October 10, 2007
ESRB: T (Teen)
Portal is a first-person puzzle-platform video game developed by Valve Corporation. The game was released in a bundle package called The Orange Box for Microsoft Windows and Xbox 360 on October 10, 2007 and for the PlayStation 3 on December 11, 2007. The Windows version of the game is available for download separately through Valve's content delivery system Steam and was released as a standalone retail product on April 9, 2008. A macOS version was released as part of the Mac-compatible Steam platform on May 12, 2010. An Android port for the Nvidia Shield was released on May 12, 2014.
The game primarily comprises a series of puzzles that must be solved by teleporting the player's character - Chell - and simple objects using the Aperture Science Handheld Portal Device, a device that can create inter-spatial portals between two flat planes.
- Party Escort Bot
- Doug Rattmann (Wall scribblings only)
- Cave Johnson (As "CJOHNSON" scribbled on a wall)
Portal`s plot is revealed to the player via audio messages from GLaDOS and visual elements in side rooms found in later levels. According to The Final Hours of Portal 2, the year is established to be "somewhere in 2010." The game begins with protagonist Chell waking up from a stasis bed and hearing instructions and warnings from GLaDOS about the upcoming test experience. This part of the game involves distinct test chambers that, in sequence, introduce players to the game's mechanics. GLaDOS's announcements serve not only to instruct Chell and help her progress through the game, but also to create atmosphere and develop the AI as a character. Chell is promised cake and grief counseling as her reward if she manages to complete all the test chambers.
Chell proceeds through the empty Enrichment Center, interacting only with GLaDOS. Over the course of the game, GLaDOS's motives are hinted to be more sinister than her helpful demeanor suggests. Although she is designed to appear helpful and encouraging, GLaDOS's actions and speech suggest insincerity and callous disregard for the safety and well-being of the test subjects. The test chambers become increasingly dangerous as Chell proceeds, and GLaDOS even directs Chell through a live-fire course designed for military androids as a result of "mandatory scheduled maintenance" in the regular test chamber, as well as having test chambers flooded with deadly liquid. In another chamber, GLaDOS boasts about the fidelity and importance of the Weighted Companion Cube, a waist-high crate with a single large pink heart on each face, for helping Chell to complete the chamber. However, GLaDOS then declares that it "unfortunately must be euthanized" in an "Emergency Intelligence Incinerator" before Chell can continue. Some of the later chambers include Sentry Turrets that fire at Chell, only to sympathize with her after being disabled ("I don't blame you" and "No hard feelings").
After Chell completes the final test chamber, GLaDOS congratulates her and prepares her "victory candescence", maneuvering Chell into a pit of fire. As GLaDOS assures her that "all Aperture technologies remain safely operational up to 4,000 degrees [sic] kelvin", Chell escapes with the use of the portal gun and makes her way through the maintenance areas within the Enrichment Center. GLaDOS becomes panicked and insists that she was only pretending to kill Chell, as part of testing. GLaDOS then asks Chell to assume the "party escort submission position", lying face-first on the ground, so that a "party associate" can take her to her reward. Chell continues forward. Throughout this section, GLaDOS still sends messages to Chell and it becomes clear that she has become corrupt. Chell makes her way through the maintenance areas and empty office spaces behind the chambers, sometimes following graffiti messages which point in the right direction. These backstage areas, which are in an extremely dilapidated state, stand in stark contrast to the pristine test chambers. The graffiti includes statements such as "the cake is a lie" and pastiches of Emily Dickinson's poem "The Chariot", Henry Wadsworth Longfellow's "The Reaper and the Flowers", and Emily Brontë's "No Coward Soul Is Mine", mourning the death of the Companion Cube.
GLaDOS attempts to dissuade Chell with threats of physical harm and misleading statements claiming that she is going the wrong way as Chell makes her way deeper into the maintenance areas. Eventually, Chell reaches the Central AI Chamber where GLaDOS's hardware hangs overhead. GLaDOS continues to plead with and threaten Chell, but during the exchange one of GLaDOS' personality core spheres falls off; Chell drops it in an incinerator. GLaDOS reveals that Chell has just destroyed the morality core, which the Aperture Science employees allegedly installed after GLaDOS flooded the enrichment center with a deadly neurotoxin, and goes on to state that now there is nothing to prevent her from doing so once again. A six-minute countdown starts as Chell dislodges and incinerates more pieces of GLaDOS, while GLaDOS attempts to discourage her both verbally, with a series of taunts and increasingly juvenile insults, and physically by firing rockets at her. After she has destroyed the final piece, a portal malfunction tears the room apart and transports everything to the surface. Chell is then seen lying outside the facility's gates amid the remains of GLaDOS. One of the final scenes is changed through a patch of the PC version and The Orange Box for Xbox that was made available a few days before Portal 2`s announcement; in this retroactive continuity, Chell is dragged away from the scene by an unseen entity speaking in a robotic voice, thanking her for assuming the party escort submission position.
The final scene, after a long and speedy zoom through the bowels of the facility, shows a Black Forest cake, and the Weighted Companion Cube, surrounded by a mix of shelves containing dozens of apparently inactive personality cores. One by one a number of the cores begin to light up, before a robotic arm descends and extinguishes the candle on the cake, plunging the room into darkness. As the credits roll, GLaDOS delivers a concluding report: the song "Still Alive", which declares the experiment to be a huge success, as well as serving to indicate to the player that GLaDOS is still alive.
In Portal, the player controls the protagonist, Chell, from a first-person perspective as she is challenged to navigate through a series of rooms using the Aperture Science Handheld Portal Device, or portal gun. The portal gun can create two distinct portal ends, orange and blue. The portals create a visual and physical connection between two different locations in three-dimensional space. Neither end is specifically an entrance or exit; all objects that travel through one portal will exit through the other. An important aspect of the game's physics is momentum redirection. As moving objects pass through portals, they come through the exit portal at the same direction as the exit portal is facing and with the same speed with which they passed through the entrance portal. For example, a common maneuver is to jump down to a portal on the floor and emerge through a wall, flying over a gap or another obstacle. This allows the player to launch objects or Chell herself over great distances, both vertically and horizontally, referred to as 'flinging' by Valve. As GLaDOS puts it, "In layman's terms: speedy thing goes in, speedy thing comes out." If portal ends are not on parallel planes, the character passing through is reoriented to be upright with respect to gravity after leaving a portal end.
Chell and all other objects in the game that can fit into the portal ends will pass through the portal. However, a portal shot cannot pass through an open portal; it will simply deactivate or create a new portal in an offset position. Creating a portal end instantly deactivates an existing portal end of the same color. Moving objects, glass, special wall surfaces, liquids, or areas that are too small will not be able to anchor portals. Chell is sometimes provided with cubes that she can pick up and use to climb on or to hold down large buttons that open doors or activate mechanisms. Particle fields known as Emancipation Grills, occasionally called "fizzlers" in the developer commentary, exist at the end of all and within some test chambers; when passed through, they will deactivate any active portals and disintegrate any object carried through. The fields also block attempts to fire portals through them.
Although Chell is equipped with Advanced Knee Replacements to prevent damage from falling, she can be killed by various other hazards in the test chambers, such as turret guns, Energy Balls, and toxic liquid. She can also be killed by objects falling through portals, and by a series of crushers that appear in certain levels. There is no health indicator; Chell dies if she is dealt a certain amount of damage in a short time period, but returns to full health fairly quickly. Some obstacles, such as the energy balls and crushing pistons, deal fatal damage with a single blow.
GameSpot noted, in its initial review of Portal, that many solutions exist for completing each puzzle, and that the gameplay "gets even crazier, and the diagrams shown in the trailer showed some incredibly crazy things that you can attempt." Two additional modes are unlocked upon the completion of the game that challenge the player to work out alternative methods of solving each test chamber. Challenge maps are unlocked near the halfway point and Advanced Chambers are unlocked when the game is completed. In Challenge mode, levels are revisited with the added goal of completing the test chamber either with as little time, with the least number of portals, or with the fewest footsteps possible. In Advanced mode, certain levels are made more complex with the addition of more obstacles and hazards.
The PC, Xbox 360 and macOS versions of the game also feature a number of achievements the player can earn by completing tasks. Achievements range from normal gameplay requirements, such as acquiring the fully operational Aperture Science Handheld Portal Device, to various tricks, such as using portals to jump a particular distance or falling 30,000 ft. As with other Source engine games since Half-Life 2, Portal can be played with developer commentary enabled.
Portal is Valve's spiritual successor to the freeware game Narbacular Drop, the 2005 independent game released by students of the DigiPen Institute of Technology; the original Narbacular Drop team is now employed at Valve. Valve became interested in Narbacular Drop after seeing the game at DigiPen's annual career fair; Robin Walker, one of Valve's developers, saw the game at the fair and later contacted the team providing them with advice and offering to show their game at Valve's offices. After their presentation, Valve's president Gabe Newell quickly offered the entire team jobs at Valve to develop the game further. Newell later commented that he was impressed with the DigiPen team as "they had actually carried the concept through", already having included the interaction between portals and physics, completing most of the work that Valve would have had to commit on their own. Certain elements have been retained from Narbacular Drop, such as the system of identifying the two unique portal endpoints with the colors orange and blue. A key difference in the signature portal mechanic between the two games however is that Portal`s portal gun cannot create a portal through an existing portal unlike in Narbacular Drop. The game's original setting, of a princess trying to escape a dungeon, was dropped in favor of the Aperture Science approach. Portal took approximately two years and four months to complete after the DigiPen team was brought into Valve, and no more than ten people were involved with its development. Portal writer Erik Wolpaw, who, along with fellow writer Chet Faliszek, was hired by Valve for the game, claimed that "Without the constraints, Portal would not be as good a game".
The Portal team worked with Half-Life series writer Marc Laidlaw on fitting the game into the series' plot. This was done, in part, due to the limited art capabilities of the small team; instead of creating new assets for Portal, they decided to tie the game to an existing franchise—Half-Life—to allow them to reuse the Half-Life 2 art assets. Wolpaw and Faliszek were put to work on the dialogue for Portal. The concept of a computer AI guiding the player through experimental facilities to test the portal gun was arrived at early in the writing process. They drafted early lines for the yet-named "polite" AI with humorous situations, such as requesting the player's character to "assume the party escort submission position", and found this style of approach to be well-suited to the game they wanted to create, ultimately leading to the creation of the GLaDOS character. GLaDOS was central to the plot, as Wolpaw notes "We designed the game to have a very clear beginning, middle, and end, and we wanted GLaDOS to go through a personality shift at each of these points." Wolpaw further describes the idea of using cake as the reward came about as "at the beginning of the Portal development process, we sat down as a group to decide what philosopher or school of philosophy our game would be based on. That was followed by about 15 minutes of silence and then someone mentioned that a lot of people like cake." The cake element along with additional messages given to the player in the behind-the-scenes areas were written and drawn by Kim Swift.
The austere settings in the game came about because testers spent too much time trying to complete the puzzles using decorative but non-functional elements. As a result, the setting was minimized to make the usable aspects of the puzzle easier to spot, using the clinical feel of the setting in the film The Island as reference. While there were plans for a third area, an office space, to be included after the test chambers and the maintenance areas, the team ran out of time to include it. They also dropped the introduction of Doug Rattmann, a character who left the messages in the maintenance areas, to avoid creating too much narrative for the game, though the character was developed further in a tie-in comic "Lab Rat", that ties Portal and Portal 2`s story together. According to project lead Kim Swift, the final battle with GLaDOS went through many iterations, including having the player chased by James Bond lasers, which was partially applied to the turrets, Portal Kombat where the player would have needed to redirect rockets while avoiding turret fire, and a chase sequence following a fleeing GLaDOS. Eventually, they found that playtesters enjoyed a rather simple puzzle with a countdown timer near the end; Swift noted, "Time pressure makes people think something is a lot more complicated than it really is", and Wolpaw admitted, "It was really cheap to make [the neurotoxin gas]" in order to simplify the dialogue during the battle.
Chell's face and body are modeled after Alésia Glidewell, an American freelance actress and voice-over artist, selected by Valve from a local modeling agency for her face and body structure. Ellen McLain provided the voice of the antagonist GLaDOS. Erik Wolpaw noted, "When we were still fishing around for the turret voice, Ellen did a sultry version. It didn't work for the turrets, but we liked it a lot, and so a slightly modified version of that became the model for GLaDOS's final incarnation." Mike Patton performed the growling and snarling voice of GLaDOS's final personality core, named the Anger Sphere.
The Weighted Companion Cube inspiration was from project lead Kim Swift with additional input from Wolpaw from reading some "declassified government interrogation thing" whereby "isolation leads subjects to begin to attach to inanimate objects"; Swift commented, "We had a long level called Box Marathon; we wanted players to bring this box with them from the beginning to the end. But people would forget about the box, so we added dialogue, applied the heart to the cube, and continued to up the ante until people became attached to the box. Later on, we added the incineration idea. The artistic expression grew from the gameplay." Wolpaw further noted that the need to incinerate the Weighted Companion Cube came as a result of the final boss battle design; they recognized they had not introduced the idea of incineration necessary to complete the boss battle, and by training the player to do it with the Weighted Companion Cube, found the narrative "way stronger" with its "death". Swift noted that any similarities to psychological situations in the Milgram experiment or 2001: A Space Odyssey are happenstance.
The portal gun's full name, Aperture Science Handheld Portal Device, can be abbreviated as ASHPD, which resembles a shortening of the name Adrian Shephard, the protagonist of Half-Life: Opposing Force. This similarity was noticed by fans before the game's release; as a result, the team placed a red herring in the game by having the letters of Adrian Shephard highlighted on keyboards found within the game. According to Kim Swift, the cake is a Black Forest cake that she thought looked the best at the nearby Regent Bakery and Café in Redmond, Washington, and, as an Easter egg within the game, its recipe is scattered among various screens showing lines of binary code. The Regent Bakery has stated that since the release of the game, its Black Forest cake has been one of its more popular items.
The popularity of the game and of its characters has led Valve to develop merchandise for Portal made available through its online Steam store. Some of the more popular items were the Weighted Companion Cube plush toys and fuzzy dice. When first released, both were sold out in under 24 hours. Other products available through the Valve store include t-shirts and Aperture Science coffee mugs and parking stickers, and merchandise relating to the phrase the cake is a lie, which has become an internet meme. Wolpaw noted they did not expect certain elements of the game to be as popular as they were, while other elements they had expected to become fads were ignored, such as a giant hoop that rolls on-screen during the final scene of the game that the team had named Hoopy.
Portal was first released as part of The Orange Box for Microsoft Windows and Xbox 360 on October 9, 2007, and for the PlayStation 3 on December 11, 2007. The Windows version of the game is also available for download separately through Valve's content delivery system Steam and was released as a standalone retail product on April 9, 2008. In addition to Portal, the Box also included Half-Life 2 and its two add-on episodes, as well as Team Fortress 2. Portal`s inclusion within the Box was considered an experiment by Valve; having no idea of the success of Portal, the Box provided it a "safety net" via means of these other games. Portal was kept to a modest length in case the game did not go over well with players. Since then, a standalone version of the game was released for Microsoft Windows users.
Portal was the first Valve-developed game to be added to the Mac OS X-compatible list of games available on the launch of the Steam client for Mac on May 12, 2010, supporting Steam Play, in which players that had bought the game either on a Macintosh or Windows computer could also play it on the alternate system. As part of the promotion, Portal was offered as a free title for any Steam user during the two weeks following the Mac client's launch. Within the first week of this offer, over 1.5 million copies of the game were downloaded through Steam. A similar promotion was held in September 2011, near the start of a traditional school year, encouraging the use of the game as an educational tool for science and mathematics. Valve wrote that they felt that Portal "makes physics, math, logic, spatial reasoning, probability, and problem-solving interesting, cool, and fun", a necessary feature to draw children into learning. This was tied to Digital Promise, a United States Department of Education initiative to help develop new digital tools for education, and which Valve is part of.
 Sequel and spin-offs
Swift stated that future Portal developments would depend on the community's reactions, saying, "We're still playing it by ear at this point, figuring out if we want to do multiplayer next, or Portal 2, or release map packs." Some rumors regarding a sequel arose due to casting calls for voice actors. On March 5, 2010, Portal 2 was officially announced, after a series of cryptic clues were released in the form of an update to Portal. It was released on April 19, 2011
 Portal: Still Alive
Portal: Still Alive is an exclusive Xbox Live Arcade game released in October 2008 that features new levels and achievements. The additional content is drawn from levels from the map based on Portal: The Flash Version by We Create Stuff and contains no additional story-related levels. According to Valve spokesman Doug Lombardi, Valve had been in discussion with Microsoft to bring Portal to the Xbox Live Marketplace, but was limited by the amount bandwidth that Microsoft was willing to allow for such content.
Portal was very well received by critics, often earning more praise than either Half-Life 2: Episode Two or Team Fortress 2 also included in The Orange Box. It was praised for its unique gameplay and dark, deadpan humor. Eurogamer cited that "the way the game progresses from being a simple set of perfunctory tasks to a full-on part of the Half-Life story is absolute genius", while GameSpy noted that "What Portal lacks in length, it more than makes up for in exhilaration." The game was criticized for sparse environments, and both criticized and praised for its short length. Aggregate reviews for the stand-alone PC version of Portal gave the game an average rating of 89% based on 27 reviews through Game Rankings, and 90% through 28 reviews on Metacritic. Upon release of Portal 2, Valve stated that Portal has sold more than four million copies through the retail versions, including the standalone game and The Orange Box, and from the Xbox Live Arcade version. This figure does not include sales figures for Valve's own Steam digital download service.
The game generated a fan following for the Weighted Companion Cube—even though the cube itself does not talk or act in the game. Fans have created plush and papercraft versions of the cube and the various turrets, as well as PC case mods and models of the Portal cake and the portal gun. Jeep Barnett, a programmer for Portal, noted that players have told Valve that they had found it more emotional to incinerate the Weighted Companion Cube than to harm one of the "Little Sisters" from BioShock. Both GLaDOS and the Weighted Companion Cube were nominated for the Best New Character Award on G4, with GLaDOS winning the award for "having lines that will be quoted by gamers for years to come."
Ben "Yahtzee" Croshaw of Zero Punctuation gave the game the only entirely positive review in the show's history, calling it "the most fun you'll have with your PC until they invent a force-feedback codpiece". Croshaw went on to say: "I went in expecting a slew of interesting portal-based puzzles and that's exactly what I got, but what I wasn't expecting was some of the funniest pitch black humor I've ever heard in a game". He states that, while the game was short, the two- to three-hour length of the game was perfect as the game did not outstay its welcome, and called the ending "balls-tighteningly fantastic", while praising the game as "absolutely sublime from start to finish".
Portal`s story has been stated to be well-established in the context of Erving Goffman's dissemination on dramaturgy, The Presentation of Self in Everyday Life, which equates one's persona to the front and back stage areas of a theater. In the case of Portal, the story carefully establishes the front stage, the pretense of the Enrichment Center, and hints at problems in the back stage through various technical faults, and then slowly reveals more and more of the back stage to the player throughout the game. Due to this, the video game was made part of the required course material among other classical and contemporary works, including Goffman's work, for a freshman course "devoted to engaging students with fundamental questions of humanity from multiple perspectives and fostering a sense of community" for Wabash College in 2010. Portal has also been cited as a strong example of instructional scaffolding that can be adapted for more academic learning situations, as the player, through careful design of levels by Valve, is first hand-held in solving simple puzzles with many hints at the correct solution, but this support is slowly removed as the player progresses in the game, and completely removed when the player reaches the second half of the game. Rock, Paper, Shotgun's Hamish Todd considered Portal as an exemplary means of game design by demonstrating a series of chambers after the player has obtained the portal gun that gently introduce the concept of flinging without any explicit instructions. Portal was exhibited at the Smithsonian Art Exhibition in America from February 14 through September 30, 2012. Portal won the "Action" section for the platform "Modern Windows."
Portal has won several awards:
- At the 2008 Game Developers Choice Awards, Portal won Game of the Year, along with the Innovation Award and Best Game Design.
- IGN honored Portal with several awards, for Best Puzzle Game for PC and Xbox 360, Most Innovative Design for PC, and Best End Credit Song (for "Still Alive") for Xbox 360, along with overall honors for Best Puzzle Game and Most Innovative Design.
- In its Best of 2007, GameSpot honored The Orange Box with 4 awards in recognition of Portal, giving out honors for Best Puzzle Game, Best New Character(s) (for GLaDOS), Funniest Game, and Best Original Game Mechanic (for the portal gun).
- Portal was awarded Game of the Year (PC), Best Narrative (PC), and Best Innovation (PC and console) honors by 1UP.com in its 2007 editorial awards.
- GamePro honored the game for Most Memorable Villain (for GLaDOS) in its Editors' Choice 2007 Awards.
- Portal was awarded the Game of the Year award in 2007 by Joystiq, Good Game, and Shacknews.
- The Most Original Game award by X-Play.
- In Official Xbox Magazine`s 2007 Game of the Year Awards, Portal won Best New Character (for GLaDOS), Best Original Song (for "Still Alive"), and Innovation of the Year.
- In GameSpy's 2007 Game of the Year awards, Portal was recognized as Best Puzzle Game, Best Character (for GLaDOS), and Best Sidekick (for the Weighted Companion Cube).
- The A.V. Club called it the Best Game of 2007.
- The webcomic Penny Arcade awarded Portal Best Soundtrack, Best Writing, and Best New Game Mechanic in its satirical 2007 We're Right Awards.
- Eurogamer gave Portal first place in its Top 50 Games of 2007 rankings.
- IGN also placed GLaDOS, as the #1 Video Game Villain on its Top-100 Villains List.
- GamesRadar named it the best game of all time.
- In November 2012, Time named it one of the 100 greatest video games of all time.
- Wired considered Portal to be one of the most influential games of the first decade of the 21st century, believing it to be the prime example of quality over quantity for video games.
Most of the game's soundtrack is non-lyrical ambient music composed by Kelly Bailey and Mike Morasky, somewhat dark and mysterious to match the mood of the environments. The closing credits song, "Still Alive", was written by Jonathan Coulton and sung by Ellen McLain as the GLaDOS character.
- ↑ 1.0 1.1
- ↑ 2.0 2.1 The Orange Box (PC). Metacritic. Retrieved on February 25, 2008.
- ↑ 3.0 3.1 3.2 The Orange Box (Xbox 360). Metacritic. Retrieved on February 25, 2008.
- ↑ 4.0 4.1 4.2 The Orange Box (PS3). Metacritic. Retrieved on 2008-02-25.
- ↑ 5.0 5.1 Kiestmann, Ludwig (2008-03-06). Individual Orange Box games hit retail April 9. Joystiq. Retrieved on 2008-03-06.
- ↑ 6.0 6.1 Hollister, Sean (April 29, 2010). Steam for Mac Opens a Portal to May 12, steps through. Engadget. Retrieved on May 11, 2010.
- ↑ 7.0 7.1 7.2 Portal commentary
- ↑ Accardo, Sal (October 9, 2007). Portal (PC). GameSpy. Retrieved on February 25, 2008.
- ↑ Elliot, Shawn (October 10, 2007). Portal (PC). 1UP. Retrieved on August 3, 2008.
- ↑ Bradwell, Tom (October 10, 2007). Portal. Eurogamer. Retrieved on February 25, 2008.
- ↑ Adams, Dan (October 9, 2007). Portal Review. IGN. Retrieved on February 25, 2008.
- ↑ 12.0 12.1 12.2 12.3 12.4 12.5 Reeves, Ben (March 10, 2010). Exploring Portal’s Creation And Its Ties To Half-Life 2. Game Informer. Retrieved on March 10, 2010.
- ↑ Faylor, Chris (March 3, 2010). Portal Mystery Deepens with Second Update. Shacknews. Retrieved on March 3, 2010.
- ↑ Coulton, Jonathan (October 15, 2007). Portal: The Skinny. Jonathan Coulton's blog. Retrieved on November 1, 2007.
- ↑ Ocampo (July 13, 2006). Half-Life 2: Episode Two — The Return of Team Fortress 2 and Other Surprises. GameSpot. Retrieved on July 21, 2006.
- ↑ Things are heating up!. Narbacular Drop official site (July 17, 2006). Archived from the original on 2007-09-28. Retrieved on July 21, 2006.
- ↑ 17.0 17.1 Berghammer, Billy (August 25, 2006). GC 06:Valve's Doug Lombardi Talks Half-Life 2 Happenings. Game Informer. Archived from the original on October 2, 2007. Retrieved on September 27, 2007.
- ↑ 18.0 18.1 18.2 Dudley, Breir (April 17, 2011). 'Portal' backstory a real Cinderella tale. Seattle Times. Retrieved on April 17, 2011.
- ↑ 19.0 19.1 Pratt (September 30, 2007). Pratt and Chief interview the Portal team at VALVe headquarters. Planet Half-Life. Retrieved on February 7, 2008.
- ↑ 20.0 20.1 20.2 Faylor, Chris (February 23, 2008). GDC 08: Portal Creators on Writing, Multiplayer, Government Interrogation Techniques. Shacknews. Retrieved on February 23, 2008.
- ↑ Irwin, Mary Jane (February 23, 2008). GDC: A Portal Postmortem. Next-Gen Biz. Retrieved on February 26, 2008.
- ↑ Leone (September 8, 2006). Portal Preview. 1UP.com. Retrieved on September 11, 2006.
- ↑ 23.0 23.1 23.2 23.3 Walker, John (October 31, 2007). RPS Interview: Valve's Erik Wolpaw. Rock, Paper, Shotgun. Retrieved on October 31, 2007.
- ↑ Pinchefsky, Carol (June 26, 2012). Kim Swift, Creator of 'Portal,' Discusses Her Latest Game, 'Quantum Conundrum'. Forbes. Retrieved on June 26, 2012.
- ↑ 25.0 25.1 25.2 25.3 25.4 25.5 Elliot, Shawn (February 6, 2008). Beyond the Box: Orange Box Afterthoughts. 1UP. Retrieved on February 14, 2008.
- ↑ McWhertor, Michael (February 23, 2008). Portal Devs Reveal the GLaDOS That Never Was, Inspiration Behind Weighted Companion Cube. Kotaku. Retrieved on February 26, 2008.
- ↑ Esposito, Joey (April 8, 2011). Portal 2: Lab Rat – Part 1. IGN. Retrieved on April 11, 2011.
- ↑ Esposito, Joey (April 11, 2011). Read Portal 2: Lab Rat – Part 2. IGN. Retrieved on April 11, 2011.
- ↑ Glidewell, Alésia. On-Camera — Alésia Glidewell — Voice Over Artist. AlesiaGlidewell.com. Archived from the original on September 3, 2011. Retrieved on April 27, 2014.
- ↑ Graff, Kris (2009-11-02). Valve's Writers And The Creative Process. Gamasutra. Retrieved on 2009-11-02.
- ↑ Geoff, Keighley (March 1, 2008). GameTrailers Episode 106. GameTrailers.com. Archived from the original on March 5, 2008. Retrieved on March 25, 2008.
- ↑ 32.0 32.1 VanBurkleo, Meagan (March 31, 2010). Let There Be Cake. Game Informer. Retrieved on March 31, 2010.
- ↑ Steam Updates: Friday, November 9, 2007. Valve (2007-11-09). Retrieved on 2007-11-09.
- ↑ De Marco, Flynn (2007-12-15). Official Plush Weighted Companion Cube Sells Out. Kotaku. Retrieved on 2008-02-21.
- ↑ Caolli, Eric (2010-05-12). Steam Launched For Mac, Portal Offered For Free. Gamasutra. Retrieved on 2010-05-13.
- ↑ Remo, Chris (2010-05-19). Portal Racks Up 1.5M Free Downloads On PC, Mac. Gamasutra. Retrieved on 2010-05-19.
- ↑ Purchase, Robert (2011-09-16). Portal free on Steam until 20th Sept. Eurogamer. Retrieved on 2011-09-16.
- ↑ Learn With Portals. learningwithportals.com. Valve Corporation (2011-09-15). Archived from the original on 2011-10-06. Retrieved on 2014-04-27.
- ↑ Kuchera, Ben (2011-09-16). Portal is used to teach science as Valve gives game away for limited time. Ars Technica. Retrieved on 2011-09-16.
- ↑ Toppo, Greg (2011-09-19). Valve teams with White House in digital learning program. USA Today. Retrieved on 2011-09-20.
- ↑ Paul, Jason (2014-03-25). What’s in the Box? Portal – Valve’s Popular PC Title – Coming to SHIELD. Nvidia. Retrieved on 2014-05-27.
- ↑ Tach, Dave (2014-05-26). Why Nvidia created its own hardware platform and started developing games. Polygon. Vox Media. Retrieved on 2014-05-27.
- ↑ Bramwell (May 15, 2007). Portal: First Impressions. Eurogamer. Retrieved on October 5, 2007.
- ↑ Plunkett, Luke (2008-06-10). Casting call reveals Portal 2 details. Kotaku. Retrieved on 2008-07-18.
- ↑ Plunkett, Luke (2008-06-10). More details on Portal 2's bad guy. Kotaku. Retrieved on 2008-07-18.
- ↑ Keil, Matt. G4 Review — The Orange Box. G4TV. Retrieved on 2007-10-19.
- ↑ Reed, Kristen (2007-10-10). The Orange Box. Eurogamer. Retrieved on 2008-02-14.
- ↑ McGarvey, Sterline (2007-10-10). The Orange Box (X360). GameSpy. Retrieved on 2008-02-14.
- ↑ Adams, Dan. IGN: Portal Review. IGN. Retrieved on 2007-10-19.
- ↑ Portal Reviews (PC). Game Rankings. Retrieved on 2009-07-05.
- ↑ Portal (pc: 2007): Reviews. Metacritic. Retrieved on 2007-10-22.
- ↑ Rose, Mike (2011-04-20). Portal Sells 4 Million Excluding Steam Sale. Gamasutra. Retrieved on 2011-04-20.
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- ↑ Cavali, Earnest (2009-01-21). Fan Crafts Gorgeous Replica Portal Gun. Wired. Retrieved on 2010-05-20.
- ↑ Winners of X-Play Best of 2007 Awards Announced—BioShock is Video Game of the Year. G4TV (2007-12-17). Retrieved on 2008-01-31.
- ↑ Neuls, Johnathan (2007-11-12). Valve to sell official Weighted Companion Cube plushies. Ars Technica. Retrieved on 2008-04-18.
- ↑ Kurchera, Ben (2008-01-02). Kiss Me, Kill Me, Thrill Me: ups and downs in gaming 2007. Ars Technica. Retrieved on 2008-04-18.
- ↑ http://www.escapistmagazine.com/videos/view/zero-punctuation/10-The-Orange-Box
- ↑ Johnson, Daniel (2009-06-01). Column: 'Lingua Franca' – Portal and the Deconstruction of the Institution. GameSetWatch. Retrieved on 2009-06-01.
- ↑ Goldman, Tom (2010-08-22). College Professor Requires Students to Study Portal. The Escapist. Retrieved on 2010-08-22.
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- ↑ Todd, Hamish (2013-09-20). Untold Riches: An Analysis Of Portal’s Level Design. Rock, Paper, Shotgun. Retrieved on 2013-09-20.
- ↑ http://www.americanart.si.edu/exhibitions/archive/2012/games/winninggames.pdf
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- ↑ IGN Best of 2007: PC Best Puzzle Game. IGN.com. Archived from the original on 2013-10-16. Retrieved on 2014-04-27.
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- ↑ GameSpot's Best of 2007: Best Puzzle Game Genre Awards. GameSpot. Archived from the original on 2008-12-05. Retrieved on 2008-02-18.
- ↑ GameSpot's Best of 2007: Best New Character(s) Special Achievement. GameSpot. Archived from the original on 2011-08-19. Retrieved on 2008-02-18.
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- ↑ X-Play Best of 2007: Most Original Game. G4 (2007-12-18). Retrieved on 2008-02-25.
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- ↑ Eurogamer's Top 50 Games of 2007. Eurogamer. Retrieved on 2008-01-01.
- ↑ IGN's top 100 villains. IGN. Retrieved on 2010-05-18.
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- ↑ Kohler, Chris (2009-12-24). The 15 Most Influential Games of the Decade. Wired. Retrieved on 2009-12-24.