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Portal 2

Ch. 1 of 8
— CH. 1 · INTRODUCTION —

Contents

Portal 2

8 sections

  • Adam Foster, a Valve employee, ran a bulletin board from his own home phone line. Valve's offices were too modern to support the old protocol. The board served ASCII pictures and scraps of Aperture Science documents to curious players. Foster estimates that the alternate reality game around it cost less than $100. It was an early hint of Portal 2, the puzzle-platform sequel that Valve released in 2011.

    The original Portal, from 2007, asked players to place portals on walls and step through them. How do you make a second game when the first was widely seen as nearly perfect? What happens to a story about a silent test subject when her captor has been destroyed? And why did a game about one person alone in a laboratory end up needing two players?

  • Portal had a team of seven or eight people. Portal 2 had 30 or 40. Work began almost immediately after the first game shipped, partly because other developers inside Valve were pressing to work on a Portal product. An initial team of four grew as subgroups formed to devise mechanics and plot the story. Some staff who had helped the Left 4 Dead games meet their milestones returned. According to writer Erik Wolpaw, they came back "with extra people in tow." Kim Swift, designer of the first game, left for Airtight Games halfway through.

    Project manager Erik Johnson described Valve's goal as finding a way to "re-surprise" players. He called that a "pretty terrifying" prospect. The first attempt avoided portals altogether. For five months the team worked on a mechanic called "F-Stop." It centered on an "Aperture Camera" that let users photograph an object, store it, and put it back down rotated or scaled. Valve kept the details quiet because it hoped to reuse the idea. In 2020, developer LunchHouse Software revealed that its game Exposure used Valve's F-Stop code.

    The F-Stop game was set in the 1980s and would not have featured Chell or GLaDOS. Its new test subject would have been caught in a conflict inside Aperture. Cave Johnson, seeking immortality, had uploaded himself into an artificial intelligence and taken control of a robot army. Playtesters liked it but missed the portals. Around October 2008, Gabe Newell told the team to reconsider its direction.

    Another early idea was a prequel set in the 1950s. In June 2008, Kotaku reported that Valve was casting a voice actor for Johnson. The report cited a casting call website and leaked script samples. Valve blamed an "overeager agent." More playtester complaints about the missing Chell and GLaDOS pushed the team to recast the project as a sequel. Johnson survived, but as a voice from the facility's past instead of the leader of an army.

    In March 2011, one month before release, Newell called Portal 2 "the best game we've ever done." After release, Geoff Keighley wrote that Newell expected it to be "probably" Valve's last game with an isolated single-player experience. Newell added that Valve was not giving up on single-player. It wanted more social features layered on top, like the cooperative mode in Portal 2.

  • Valve did not want Portal 2 to be harder than its predecessor. The stated aim was "a game where you think your way through particular parts of the level, and feel really smart when you solve it." To teach the rules step by step, designers built two kinds of test chamber. One, which Valve called "checklisting," offered a safe space to try a new concept. The other combined known elements in fresh ways, so that players had to think laterally.

    Each chamber began as an isometric drawing on a whiteboard. After a sanity check, designers built simple versions in the Hammer Editor, Valve's level construction tool. Playtesting then tuned the difficulty so that solutions were neither too obvious nor too hard. When testers found alternative solutions that were too easy, the team removed them.

    The toolkit grew well beyond the Aperture Science Handheld Portal Device. Thermal Discouragement Beams, Excursion Funnels, and Hard Light Bridges can all pass through portals. Aerial Faith Plates catapult people and objects through the air. Redirection Cubes carry prismatic lenses that bend laser beams. Pneumatic Diversity Vents appeared in early demonstrations but never reached the final game. The moving energy balls of the first game gave way to lasers, which give players immediate feedback.

    The gels have a separate lineage. Orange Propulsion Gel speeds players across a surface. Blue Repulsion Gel makes them bounce. White Conversion Gel lets a surface accept portals. The first two began in Tag: The Power of Paint, whose creators Valve hired to develop the idea. Journalists have likened Tag to Narbacular Drop, the DigiPen student project whose mechanics became Portal. Tag's third gel let characters walk on any surface regardless of gravity. It gave playtesters motion sickness, so Conversion Gel replaced it.

    Returning players meet rooms from the first game again. Valve rebuilt them with higher-resolution textures and added decay, collapse, and overgrowth to suggest that time had passed. The middle of the campaign opens into huge spaces where few surfaces accept portals. Designers drew on photographs of CERN, NASA facilities, and the abandoned Soviet space program. Later, when Wheatley runs the facility, the designers "had a blast" building chambers that reflect his stupidity. Between puzzles they inserted occasional "experiences," so that players could rest while the plot moved forward.

    Wolpaw estimates that each campaign runs about six hours. Valve says each one is two to two and a half times as long as the campaign in Portal. The whole game is five times as long. Developer commentary unlocks chapter by chapter, on node icons scattered through the chambers.

  • Wolpaw likened the origin of the cooperative mode to friends working through point-and-click adventure games at one computer. Players had been gathering around a single machine or console to solve Portal's puzzles, and they told Valve about it. Valve also noticed that fans of its Left 4 Dead cooperative games liked to talk about their experiences afterward.

    Every cooperative chamber demands actions from both players. Whenever a playtester found a way to finish a puzzle with only one set of portals, the level went back to the designers. With few exceptions, the two players stay in sight of each other to encourage talk. Some chambers are asymmetric, with one player working the portals so the other can cross the room. Designers found that tagging surfaces with instructional icons worked better than spoken directions. Players can also ping, start countdown timers, wave, and hug. Valve concedes that these levels are much harder than the single-player ones. It used timed puzzles here, though it had left them out of both single-player campaigns.

    Valve also built a competitive mode. Wolpaw said it resembled Speedball. One team carried a ball across the field through portals while the other tried to stop them with portals of their own. Matches quickly descended into chaos. Players clearly preferred solving puzzles, so the team dropped the idea.

    The two robots, Atlas and P-Body, were first imagined as Chell and a human character called "Mel." Once the designers switched to robots, they kept GLaDOS's jokes about the humans' "image issues." The robots hold hands. They use "expressive noises" instead of speech, and were designed as a double act in the manner of Laurel and Hardy. Dee Bradley Baker, who had voiced similar robots for Star Wars: The Clone Wars media, gave them their sounds.

    Chet Faliszek wrote GLaDOS's cooperative lines. He and Wolpaw knew that partners might talk over any story. So they kept key jokes short and repeated them often. The robots' tale is set after the single-player story. GLaDOS sends them to recover data disks from the depths of Aperture. After each mission she takes them apart and rebuilds them for the next.

    She is delighted at first. Later she sours, because the robots cannot truly die, and she grows uneasy about how close they are. At the end, the robots open the Vault, which holds thousands of humans in stasis. GLaDOS thanks them for the new test subjects and destroys them.

    The free Peer Review content, released on the 4th of October 2011, reactivates the robots a week later. The saboteur they hunt is a bird pecking at a console. It sends GLaDOS into a panic, because it once tried to eat her while she was a potato battery. She orders the eggs in its nest brought to her chamber. Her plan is to raise the chicks as killing machines.

  • Chell wakes in a stasis chamber that looks like a motel room, in a facility that seems to have decayed for millennia. At the end of the first Portal she had destroyed GLaDOS. A figure Wolpaw later named the "Party Escort Bot" then dragged her back inside. A promotional comic shows Doug Rattmann, the estranged employee whose graffiti guided players in Portal, putting her into suspended animation. The Portal series shares a universe with Half-Life, and most of this story takes place "a long time after" the first game.

    A personality core named Wheatley, voiced by Stephen Merchant, leads Chell through the old chambers. While trying to restore power to the escape pods, they accidentally wake GLaDOS, voiced by Ellen McLain. She separates them and begins rebuilding. Chell and Wheatley sabotage her production of turrets and neurotoxin, then force a core transfer that makes Wheatley the controller. He is instantly driven mad with power. He puts GLaDOS on a potato battery. GLaDOS tells Chell that Wheatley was built as an "intelligence dampening sphere," meant to produce illogical thoughts. Wheatley then wrecks the lift, and Chell and GLaDOS fall to the abandoned lowest levels.

    Down there, recordings by Aperture's eccentric founder, Cave Johnson, tell a story of decline. He is voiced by J. K. Simmons. In the 1950s, the company's test subjects were "astronauts, war heroes, and Olympians." By the 1970s they were homeless people, and by the 1980s they were Aperture's own employees. In 1981 Johnson fell mortally ill after ingesting moon dust used to make portal-conductive surfaces. He asked that his assistant Caroline be moved by force, if necessary, into a computer built to hold a human mind. That computer became GLaDOS. The discovery that she is Caroline troubles her deeply.

    The climax pits Chell against Wheatley, who has discovered the cooperative robots and decided that Chell is no longer useful. She attaches corrupted cores, voiced by Nolan North, to force another transfer. Wheatley smashes the button needed to start it. As the facility crumbles, Chell places a portal on the Moon, and the vacuum begins to pull her and Wheatley toward space. GLaDOS regains control, saves Chell, and abandons Wheatley. She then deletes Caroline's personality and decides that Chell is not worth killing. She sends her out with the burnt companion cube.

    Wolpaw and Jay Pinkerton, a former National Lampoon writer, wrote the single-player story. The game has 13,000 lines of dialogue. Wolpaw said that while some developers were moving toward art games, nobody had made a comedic one. The Caroline subplot came out of a scare. The writers realized their plan to have Chell and GLaDOS play off each other would only work if both spoke. So they gave GLaDOS something to struggle with instead.

    Playtesters had also been disoriented by an early version with a new protagonist, because GLaDOS did not recognize that character. Chell returned in her orange jumpsuit, now tied at the waist for freedom of movement. Her face is again based on voice actress Alésia Glidewell. The ending once had Chell speak a single word, but it was not funny enough.

    Scrapped ideas were stranger. One joke ending had the player asphyxiate after firing a portal at the Moon. That idea became the real finale. An early script had Chell find a lost tribe of turrets looking for a huge "Animal King" turret. The writers also planned about six personality cores, including ones based on Red from The Shawshank Redemption and Quint from Jaws. They kept only Wheatley and recycled three of the rest in the boss fight. Karen Prell, a veteran Muppets performer, led the animation team for the cores.

    Wolpaw avoided the memes of the first game, especially "the cake is a lie." He said, "if you thought you were sick of the memes, I was sick of it way ahead of you." He still allowed himself one cake joke. Portal 2 made its own memes, including a space-obsessed core. Valve later made a Space Core modification for The Elder Scrolls V: Skyrim. The character also appeared as a laser engraving on a panel manufactured by NASA for the International Space Station.

    The writers wanted a second voice to play against Johnson but did not want another actor. They asked McLain to voice Caroline too. For Wheatley, they assumed Merchant would be unavailable and contacted Graham Linehan, a writer for The IT Crowd, about Richard Ayoade. Then they found that Merchant was interested. He recorded for around sixteen hours and was free to improvise.

    Richard McCormick of PlayStation 3 Magazine read the story through the myth of Prometheus. He saw GLaDOS as Prometheus, bound to a rock and pecked by birds, and Wheatley as Prometheus' foolish brother Epimetheus. The word "Tartarus" appears on columns in the depths of Aperture.

    Valve's composer, Mike Morasky, wrote both scored and procedurally generated music. Jonathan Coulton recorded "Want You Gone" for the single-player credits. The National's "Exile Vilify" plays in one of the Rat Man's dens. The soundtrack, titled "Songs to Test By," came out as three free downloads between May and September 2011. In October 2012 it returned as a retail Collector's Edition that also included the soundtrack from Portal.

  • On the 1st of March 2010, Valve patched the original Portal with an achievement called "Transmission Received." It required players to manipulate in-game radios, which revealed new sound effects. Some were Morse code suggesting that GLaDOS was rebooting. Others decoded into grainy images from Aperture Science videos. A second patch on the 3rd of March changed the ending to show Chell being pulled back inside. Journalists guessed that an announcement was close. On the 5th of March, Game Informer put Portal 2 on the cover of its April issue.

    The teasing continued. Gabe Newell's acceptance speech for the Pioneer Award at the Game Developers Conference 2010 ended with a fake blue screen of death. It carried a message supposedly from GLaDOS. Two weeks before E3, journalists received an email styled as an Aperture Science press release. It promised "a surprise." Many guessed it meant Half-Life 2: Episode Three. Instead, it was the announcement of Portal 2 on PlayStation 3.

    Doug Lombardi had been let down by earlier agency work. He called it "Copycat treatments. Cliché treatments." So Valve adjusted its television commercials using viewer feedback, and they took eight weeks to finish. Online videos with J. K. Simmons narrating as Cave Johnson formed what Newell called a "documentary-style investment opportunity." A video released on the 14th of February 2011 pitched the cooperative mode as a St. Valentine's gift. It "lit up our preorders, our buzz, all the metrics," in the words of Lombardi. He said the videos "dwarfed the demos and interviews we did."

    Release dates slipped twice. The March 2010 announcement promised late 2010. In August 2010, Valve moved to February 2011, with a Windows date of the 9th of February. It needed time to finish dialogue changes, to fill and connect about sixty test chambers, and to refine the gels. In November 2010, Valve announced a further delay, to the week of the 18th of April 2011. Wolpaw said the eight extra weeks went toward content before an internal "content lock." The rest was debugging. Portal 2 became Valve's first product released simultaneously for Windows and Mac OS X through Steam. Electronic Arts distributed the retail copies and the console versions.

    On the 1st of April 2011, Valve released the Potato Sack, a second alternate reality game, made with several independent developers. Players coordinated through web sites and chat rooms to solve a multi-tiered puzzle. Some journalists took it as a sign that the game would arrive on the 15th of April, not on the target of the 19th. On the 15th, players found "GLaDOS@Home," a spoof of distributed computing. Once they finished the puzzles, Portal 2 unlocked at around 21:30 PST on the 18th of April. That was roughly ten hours before its planned 7:00 PST release.

    The PlayStation 3 version had surprised the industry, because Newell had criticized that console after the port of The Orange Box. His frustration with Microsoft's rules for Xbox 360 content, including how hard it was to ship patches, helped change his mind. Portal 2 was the first PlayStation 3 game to support a subset of Steamworks, including automatic updates and downloadable content. Owners could link a Steam account and play on Windows for free. A patch in November 2012 added PlayStation Move support under the name Portal 2 In Motion. PlayStation cross-play ended in 2016. Separately, Sixense built a Razer Hydra version for PC with ten extra single-player levels.

    A Linux beta arrived in early 2014, and the Xbox 360 version joined Xbox One backward compatibility in June 2016. On the 28th of June 2022, Portal 2 reached Nintendo Switch in the Portal: Companion Collection, developed by Valve and Nvidia Lightspeed Studios.

  • On the 10th of May 2011, Valve released beta modding tools. That month the mapping site Thinking with Portals held a competition with Valve's support. The bigger step was the Perpetual Testing Initiative, a free update released on the 8th of May 2012. It added a level editor and a way to share maps through the Steam Workshop. Within days, players had made 35,000 maps, downloaded 1.3 million times. Within a month, more than 150,000 user-made maps existed. A patch in August 2012 let players build cooperative levels too.

    Entire campaigns followed. Ruslan Rybka's Thinking with Time Machine, from 2014, lets players record actions that a duplicate then replays. Also in 2014, the Aperture Tag Team released a mod that swaps the portal gun for a gel gun, echoing Tag. Portal Stories: Mel, by Prism Studios, a group of eight fans, appeared on the 25th of June 2015. Portal Reloaded, by Jannis Brinkmann, launched on the 19th of April 2021, exactly ten years after the game itself. It adds a third "time portal." Portal: Revolution, from Second Face Software, followed on the 6th of January 2024.

    Valve also lent assets and help to other developers. Supergiant Games' Bastion includes a weapon inspired by Conversion Gel. Wolpaw assisted its writing, and McLain voiced new turret lines. Gary Hudston commissioned a custom single-player map, with extra GLaDOS lines from Wolpaw and McLain. He used it to propose to his fiancée, Stephanie. Valve collaborated with Zen Studios on a Portal 2 pinball table. Lego Dimensions gained a Portal 2 set, with McLain, Merchant, and Simmons reprising their roles. Coulton wrote a new GLaDOS credits song for it.

    In June 2012, Valve announced "Teach with Portals" and "Steam for Schools." Mathematics and science teachers had written to tell Valve how they used Portal in lessons. Developers Joshua Weier and Yasser Malaika led a team that looked at educational uses. They chose to provide tools rather than curricula. The result was Puzzle Maker, an editor easier to learn than Hammer, built with a mathematics teacher and her students. In November 2012, Valve estimated that over 2,500 educators were using the program.

    Seth Schiesel, writing for the New York Times, predicted that "Somewhere out there an innovative, dynamic high school physics teacher will use Portal 2 as the linchpin of an entire series of lessons." Researchers took notice too. A 2014 study found that Portal 2 can improve problem solving, spatial skills, and persistence, even for people with no gaming experience. In 2016, a study showed that Puzzle Maker chambers could measure fluid intelligence. That test, called the Portal 2 Test Battery, was comparable to the Bochumer Matrices Test. A 2017 study linked commercial games like it with gains in communication, adaptability, and resourcefulness.

  • At E3 2010, closed-door previews made Portal 2 a favorite of journalists. The Game Critics Awards named it Best PC Game and Best Action/Adventure Game. IGN named it Best of E3 for several platforms, and GameSpy called it the Best Overall Game of the show. The Spike Video Game Awards named it the "Most Anticipated Game for 2011."

    Eurogamer's Oli Welsh set the tone for the release reviews. He wrote, "Portal is perfect. Portal 2 is not. It's something better than that." IGN's Charles Onyett said the sequel "makes the original look like the prototype it was." Reviewers praised the writing and voice acting. Game Informer's Adam Biessener rated Johnson above GLaDOS. Tom Hoggins of The Telegraph admired a "brilliant learning curve of direction, rather than instruction." Welsh called the cooperative mode "one of the most satisfying and genuinely collaborative gaming experiences you can have with a friend."

    Not everyone agreed. Peter Bright of Ars Technica missed the loneliness of the first game. He wrote that "the inane babble served only to disrupt the mood." He also felt the game was "on rails." PC Gamer's Dan Stapleton found the gels "difficult to control." Some reviewers found the second act confusing. Chris Kohler of Wired complained about "sterile, duplicated, non-interactive environments." Ben "Yahtzee" Croshaw called it a "very good game." But he said it retconned the original's story. He preferred the co-op, which he found "much more within the spirit of the original."

    On the 20th of April 2011, some customers launched a protest. They said the game was too short, with some claiming only four hours. They also objected to paid downloadable content on some versions. Stephen Totilo of Kotaku replied that the game lasted nine hours and that the content was cosmetic.

    Sales were strong. Portal 2 topped Amazon's United States sales in its first week. It became the first Valve game to reach number one in the United Kingdom. NPD counted 637,000 copies in the United States in April 2011, without counting Steam. On the 22nd of June 2011, Newell announced 3 million copies sold. By May 2012, it had shipped more than 4 million units, with the PC and OS X versions outselling the consoles. Together, Portal and Portal 2 had shipped more than 8 million.

    The awards ran long. Portal 2 won "Ultimate Game of the Year" at the 2011 Golden Joystick Awards. It was the most-nominated title at the 2011 Spike Video Game Awards. It won three British Academy Games Awards, for Best Game, Best Story, and Best Design. At the Game Developers Choice Awards it won for narrative, audio, and design. In 2016, Steam users nominated it for the Steam Awards. It won "Villain Most In Need Of A Hug."

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Updated

Common questions

Who is the main character of Portal 2?

Players control Chell in the single-player campaign. In the cooperative campaign, they play the robots Atlas and P-Body.

What are the gels in Portal 2?

The gels are paint-like substances dispensed from pipes. Orange Propulsion Gel speeds movement, blue Repulsion Gel makes players bounce, and white Conversion Gel lets surfaces accept portals.

Who voices GLaDOS, Wheatley, and Cave Johnson?

Ellen McLain voices GLaDOS, who also voices Caroline. Stephen Merchant voices Wheatley, and J. K. Simmons voices Cave Johnson.

Can players make their own levels?

Yes. The Perpetual Testing Initiative, released on the 8th of May 2012, added a level editor and sharing through the Steam Workshop.

Was Portal 2 used in education?

Yes. In June 2012, Valve launched Teach with Portals and Steam for Schools, which offered Portal 2 and the Puzzle Maker editor to educators free of charge.

All sources

273 references cited across the entry

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  44. 44F-Stop, the secret mechanic of Valve's unreleased Portal prequel, has finally been revealedCraig Pearson — January 2, 2020
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  46. 46All the leaks for the Portal prequel F-Stop have been compiled into a playable gameJackson Chen — November 1, 2026
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  56. 56Water Flow in Portal 2Alex Vlachos — July 28, 2010
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  65. 65More details on Portal 2's bad guyLuke Plunkett — Kotaku — June 10, 2008
  66. 66MagazineChell Almost Married A Turret In Portal 2Tim Turi — September 1, 2012
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  68. 68Portal 2's Writer Didn't Try to Reinvent the CakeSusan Arendt — The Escapist — March 14, 2011
  69. 69Impressions: Skyrim's Portal 2 ModNathan Grayson — GameSpy — February 7, 2012
  70. 70NASA launches Portal 2 character into orbitTom Phillips — Eurogamer — July 22, 2012
  71. 71Portal 2: Test SubjectsDan Griliopoulos — IGN — March 28, 2011
  72. 72Portal 2: Lab Rat – Part 1Joey Esposito — April 8, 2011
  73. 7310 incredible Portal 2 secrets you might have missedRichard McCormick — July 17, 2011
  74. 74Portal 2 Easter Egg Video: Finding BorealisStephen Johnson — G4 TV — April 20, 2011
  75. 75Wolpaw: Players Don't Care About Portal's ChellBrenna Hillier — VG24/7 — March 14, 2011
  76. 76MagazineRedesigning Portal: Valve's Artist SpeaksBen Reeves — March 22, 2010
  77. 77The New Look For Portal 2's Heroine ExplainedMichael McWheator — Kotaku — February 23, 2011
  78. 78Meet the real-life Chell from Portal 2Computer and Video Games — March 29, 2011
  79. 79Valve: Portal's Chell is Silent Because It's FunnierTom Goldman — The Escapist — May 7, 2011
  80. 80Writing Valve's silent protagonistsBrendan Sinclair — GameSpot — October 12, 2011
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  82. 82Being Nathan Drake – InterviewJohnny Minkley — Eurogamer — May 9, 2011
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  85. 85Portal 2 Hands-onChristian Donlan — Eurogamer — February 4, 2011
  86. 86NewsGLaDOS, the greatest video game villain of all time, is back for more cake and chaos in Portal 2Andrew Ramadge — News.com.au — February 21, 2011
  87. 87MagazinePortal 2 Gains a Talkative CompanionGus Mastrapa — June 16, 2010
  88. 88MagazinePortal 2 Has A Release Date And A New Voice ActorPhil Kollar — August 18, 2010
  89. 89PAX: Portal 2 Nabs J. K. SimmonsGreg Miller — IGN — March 11, 2011
  90. 90BookPortal 2: Collector's Edition GuideGardners Books — 2011
  91. 91PAX Prime 2010: Portal 2 Co-Op Hands-On ImpressionsStephen Johnson — G4 TV — September 3, 2010
  92. 92Portal 2 previewEmanuel Maiberg — GamePro — January 21, 2011
  93. 93FAQs About the Portal 2 SongJonathan Coulton — jonathancoulton.net — April 29, 2011
  94. 94Portal 2 Ending Song: Want You Gone by Jonathan Coulton Video and LyricsDana Vinson — G4 TV — April 20, 2011
  95. 95NewsThe National To Provide Song For Portal 2John Walker — March 11, 2011
  96. 96The National Release "Exile Vilify" off Portal 2 SoundtrackNathan Spicer — April 19, 2011
  97. 97Valve offers Portal 2 soundtrack for freeFred Dutton — May 25, 2011
  98. 98Portal 2: Songs To Test By (Collector's Edition) due next monthJeffrey Matulef — Eurogamer — September 25, 2012
  99. 99More Portal for sure – ValvePurchese, Rob — Eurogamer — January 31, 2008
  100. 100Portal
  101. 101Valve Releases the Pressure
  102. 102GDC 08: Portal Creators on Writing, Multiplayer, Government Interrogation TechniquesChris Faylor — Shacknews — February 23, 2008
  103. 103Anatomy of an Alternate-Reality GameAlex Wawro — GamePro — April 26, 2010
  104. 104Portal Patch Adds Morse Code, Achievement – Portal 2 Speculation Begins (Updated)Alice O'Connor et al. — Shacknews — March 1, 2010
  105. 105Portal 2 Easter egg: Valve never meta-ARG it didn't likeJC Fletcher — Joystiq — April 20, 2011
  106. 106The first anyone had seen publicly of Portal 2 was relayed over this modem from 1987 from my kitchenRobert Purchase — Eurogamer — June 7, 2013
  107. 107Alternate Reality Game puzzle designAdam Foster — Gamasutra — June 18, 2013
  108. 108Portal Mystery Deepens with Second UpdateChris Faylor — Shacknews — March 3, 2010
  109. 109MagazineGeeky Clues Suggest Portal Sequel Is ComingGus Mastrapa — March 2, 2010
  110. 110Rumor: Valve To Make Portal 2 Announcement During GDC 2010Jake Gaskill — March 3, 2010
  111. 111Portal 2 is official, first image insideAndrew Webster — March 5, 2010
  112. 112Portal 2 Hijacks Blue Screen of Death At GDC AwardsLuke Plunkett — Kotaku — March 11, 2010
  113. 113E3 Portal 2 event replaced by "surprise"Robert Purchase — Eurogamer — June 2, 2010
  114. 114Valve Delays Portal 2, Confirms E3 Surprise Is 'PORTAL-2-THEMED-FOR-GOD'S SAKE'Chris Faylor — Shacknews — June 9, 2010
  115. 115Valve's E3 surprise is... oh. Portal 2 on PS3Tom Francis — PC Gamer — June 15, 2010
  116. 116MagazinePotato Sack Developers Helped Design Portal 2 ARGNathan Brown — April 20, 2011
  117. 117Portal 2 to get early release on Steam?Tom Phillips — April 13, 2011
  118. 118Portal 2 to release early? Potato sack ARG signs point to "yes"Nathan Greyson — VG247 — April 13, 2011
  119. 119Portal 2 levels appear in potato sack games, clues suggest Portal 2 could be released earlyTom Senior — April 13, 2011
  120. 120MagazineValve May Release Portal 2 On Friday, Not TuesdayChris Kohler — April 13, 2011
  121. 121Play indie games, help Portal 2 release earlyPete Davidson — GamePro — April 15, 2011
  122. 122MagazinePlay Steam Games, Launch Portal 2 EarlyJason Schreier — April 15, 2011
  123. 123No more potatoes: Portal 2 available right now on SteamBrenna Hillier — VG247 — April 18, 2011
  124. 124Portal 2 unlocked early with potato powerAlice O'Connor — April 18, 2011
  125. 125Valve's in-house Portal 2 ad the result of "copycat" agency treatments (Update)Brenna Hillier — VG247 — March 17, 2011
  126. 126NewsTrailer Park: 'Portal 2'Brett Molina — March 22, 2011
  127. 127Portal 2 goodies now on salePete Davidson — GamePro — April 19, 2011
  128. 128MagazinePortal 2Meagan VanBurkleo — April 2010
  129. 129Portal 2 due out this ChristmasTom Bramwell — March 5, 2010
  130. 130Portal 2 Teleports to Shelves Next FebruaryGregory Gay — The Escapist — August 18, 2010
  131. 131Portal 2 Delayed to 'The Week of April 18'Xav de Matos — Shacknews — November 18, 2010
  132. 132Newell: Portal 2 'pretty much' ready for releaseFebruary 19, 2011
  133. 133Steam Coming to Mac in April, Portal 2 This FallChris Faylor — Shacknews — March 8, 2010
  134. 134EA, Valve Confirm Distribution Agreement For Portal 2Kris Graff — Gamasutra — December 22, 2010
  135. 135NewsElectronic Arts picks up Portal 22010-12-22
  136. 136Portal 2 and Left 4 Dead receive Xbox One backwards compatibilityJeffrey Matulef — June 16, 2016
  137. 137Portal and Portal 2 coming to Nintendo SwitchNicole Carpenter — February 9, 2022
  138. 138Portal and Portal 2 coming to Nintendo SwitchTom Phillips — February 9, 2022
  139. 139Valve Apologizes For Sony-Bashing, Announces Portal 2 for PS3Matt Peckham — June 15, 2010
  140. 140Portal 2, Steamworks PS3-bound in 2011Tor Thorsen — GameSpot — June 15, 2010
  141. 141Portal 2 PS3 Has Cross-Platform Multiplayer, Free PC VersionKris Graft — January 18, 2011
  142. 142Portal 2 PS3, Steam cross-platform playWesley Yin-Poole — Eurogamer — January 18, 2011
  143. 143Valve details PS3 Steam support for Portal 2April 13, 2011
  144. 144Valve 'no plans' for 3D, Move support in Portal 2Tim Ingham — Computer and Video Games — June 22, 2010
  145. 145Portal 2 on PS3 Will Not Feature Move Support (Updated)Steve Watts — Shacknews — February 17, 2011
  146. 146Portal Picks Up a PlayStation Move Controller, Returns to the PS3 With New LevelsLuke Plunkett — Kotaku — June 5, 2012
  147. 147Portal 2 'In Motion' DLC out in US today, launch trailerMike Jackson — Computer & Video Games — November 6, 2012
  148. 148Portal 2's Move-based In Motion DLC gets a free co-op campaignJeffrey Matulef — Eurogamer — June 6, 2013
  149. 149Core Portal 2 game is the same "whether you buy it on PS3 or 360", says ValveStephany Nunneley — VG247 — January 22, 2011
  150. 150Review: The Razer Hydra Savages Portal 2 (In a Good Way!)Gord McLeod — GeekBeat.tv — June 24, 2011
  151. 151Portal 2 First DLC Content, Designed Specifically For Razer Hydra ControllerJillian Horsey — June 20, 2011
  152. 152Why Portal 2 doesn't support PS MoveWesley Yin-Poole — Eurogamer — February 25, 2011
  153. 153CES: Razer Gets Portal 2 ExclusivesLevi Buchanan — IGN — January 8, 2011
  154. 154NewsPortal 2 has hidden interactive Super 8 teaser levelTom Senior — April 19, 2011
  155. 155Portal 2 has item store, trading coming soonTom Senior — April 19, 2011
  156. 156Portal 2's Creators On Crafting Games Through Experiential StoriesKevin Ohannessian — Fast Company — April 27, 2011
  157. 157Portal 2 DLC release dateFred Dutton — Eurogamer — September 30, 2011
  158. 158Free Portal 2 DLC out next monthFred Dutton — Eurogamer — August 18, 2011
  159. 159Portal 2 Peer Review DLC is 1.37GBRobert Purchase — Eurogamer — October 4, 2011
  160. 160Portal 2 Peer Review DLC: fun, but missing the magicPeter Bright — Ars Technica — October 9, 2011
  161. 161Valve Offering Free Portal 2 DLC On All Available Platforms This SummerKyle Orland — Gamasutra — April 29, 2011
  162. 162NewsFree DLC for 'Portal 2' launching this summerBrett Molina — April 29, 2011
  163. 163Bastion on PC? Now you're thinking with portalsArs Technica — August 22, 2011
  164. 164Press releasePortal's GLaDOS Invades the World of Defense Grid!Hidden Path Entertainment
  165. 165MagazineCustom 'Portal 2' Video Game Level Built for Marriage ProposalEvan Narcisse — August 23, 2011
  166. 166Behind The Scenes Of The Portal ProposalChris Morris — Gamasutra — August 26, 2011
  167. 167Skyrim gets HD texture pack, Portal 2 Space SphereAlice O'Conner — Shacknews — February 7, 2012
  168. 168Portal Pinball: hands-on with Pinball FX2's new Portal themed tableTom Marks — May 5, 2015
  169. 169Portal, Dr. Who, The Simpsons and more confirmed for Lego DimensionsMichael McWhertor — Polygon — May 10, 2015
  170. 170Portal 2 Mod Levels 'For All Platforms'NowGamer — January 24, 2001
  171. 171Now You Can Make Your Own Custom Portal 2 Puzzles (I Said NOW!!)Michael McWhertor — Kotaku — May 10, 2011
  172. 172Portal 2 mapping contest kicks offTom Senior — May 26, 2011
  173. 173'Portal 2' puzzle creator launches May 8Brett Molina — April 26, 2012
  174. 174'Portal 2' gets level creation tools May 8th for PC and MacGriffin McElroy — Polygon — April 26, 2012
  175. 175Valve Tinkering With an Excellent Portal 2 Feature That Talks BackStephan Tolito — Kotaku — October 18, 2011
  176. 176Portal 2 Puzzle Creator in internal beta testing now, will use Steam WorkshopTom Senior — March 14, 2012
  177. 177Portal 2 Sees Map Editor Next YearFrank Cifaldi — Gamasutra — October 21, 2011
  178. 178MagazinePortal 2's Perpetual Testing Initiative Off To A Good StartMatt Helgeson — May 10, 2012
  179. 179Valve Announces Documentary Film on Pro Gaming, Portal 2 Co-Op Map MakerMike Sharkley — GameSpy — August 17, 2012
  180. 180NewsThe best Portal 2 modsCraig Pearson — December 20, 2021
  181. 181Portal 2 mod Thinking With Time Machine now available on SteamPhil Savage — April 22, 2014
  182. 182MagazineThis Portal 2 Mod Lets You Play Against YourselfBo Moore — April 28, 2014
  183. 183Portal 2 mod Aperture Tag releases on Steam, for a pricePhil Savage — July 16, 2014
  184. 184MagazineFan Made Portal 2 Mod Looks Good Enough To Be From ValveKyle Hillard — January 31, 2015
  185. 185Portal Reloaded mod adds a third portal that lets you travel through timeMollie Taylor — April 20, 2021
  186. 186Portal Reloaded adds a third portal and the fourth dimensionJody Macgregor — November 4, 2020
  187. 187Portal 2's game-sized prequel mod squeezes in 40 new puzzles, fully-voiced original characters, and an 8-hour storyKaan Serin — January 6, 2024
  188. 188Portal 2 for PCGameRankings
  189. 189Portal 2 for X360GameRankings
  190. 190Portal 2 for PS3GameRankings
  191. 191Portal 2 for PC Reviews, Ratings, Credits, and MoreMetacritic
  192. 192Portal 2 for Xbox 360 Reviews, Ratings, Credits, and More at MetacriticMetacritic
  193. 193Portal 2 for PlayStation 3 Reviews, Ratings, Credits, and More at MetacriticMetacritic
  194. 1942010 WinnersGame Critics Awards — July 6, 2010
  195. 195NewsE3 2010: Game Critics Awards nominees announcedMike Snider — June 29, 2010
  196. 196E3 2010: Best of E3 AwardsIGN — June 17, 2010
  197. 197GameSpy's Best of E3 2010 AwardsGameSpy — June 25, 2010
  198. 198Spike VGA 2010 winners – Red Dead Redemption scoops GOTYJoe Anderson — VG247 — December 10, 2010
  199. 199Critical Reception: Valve's Portal 2Danny Cowen — April 20, 2011
  200. 200Narrowly beats The Elder Scrolls V: Skyrim on Xbox 360 to take the top review spotTom Ivan — January 13, 2012
  201. 201Portal 2 ReviewMike Nelson — 1UP.com
  202. 202Portal 2Oli Welsh — April 19, 2011
  203. 203NewsReview: 'Portal 2' aces the sequel testBrett Molina — April 19, 2011
  204. 204NewsPortal 2 is for smarty-pants onlyChad Sapieha — May 1, 2011
  205. 205Portal 2 Review – Xbox 360Morgan Webb — G4 TV — April 19, 2011
  206. 206NewsPortal 2 – ReviewNick Cowen — April 19, 2011
  207. 207NewsPortal 2 – reviewWill Freeman — April 23, 2011
  208. 208NewsPortal 2 Is A Hole In OneRyan Kuo — April 19, 2011
  209. 209Portal 2Gus Mastrapa — The A.V. Club — April 25, 2011
  210. 210Portal 2 ReviewCharles Onyett — IGN — April 19, 2011
  211. 211News'Portal 2' sure to gel with fansGarrett Martin — April 25, 2011
  212. 212News'Portal 2' is a dark, humorous joy (and that's no lie)Larry Frum — CNN — April 19, 2011
  213. 213MagazinePortal 2 Review: Our First Perfect 10Evan Narcisse — April 19, 2011
  214. 214Portal 2 reviewDan Stapleton — April 19, 2011
  215. 215MagazinePortal 2 ReviewApril 19, 2011
  216. 216Magazine'Portal 2' videogame review: Physics is phunnyJohn Young — April 20, 2011
  217. 217MagazinePortal 2Adam Biessener — April 18, 2011
  218. 218Thinking on rails: why Portal 2 isn't as good as the originalPeter Bright — Ars Technica — May 2, 2011
  219. 219NewsPhysics, With Wormholes by YouSeth Schiesel — May 10, 2011
  220. 220Japan Review Check: Portal 2, Ghost ReconKevin Gifford — 1UP.com — May 11, 2011
  221. 221Portal 2 ReviewChris Watters — April 19, 2011
  222. 222Portal 2 Review (Multi-Platform)Kirk Hamilton — April 26, 2011
  223. 223MagazinePortal 2 ReviewJeff Kohler — April 21, 2011
  224. 224The Escapist : Building Sequels BadlyEscapistmagazine.com — May 10, 2011
  225. 225Fans protest Portal 2 on MetacriticDavid Jenkins — GamesIndustry.biz — April 20, 2011
  226. 226Portal 2 hit by user review backlash on Metacriticmetrowebukmetro — April 20, 2011
  227. 227The People are Panning Portal2Tolito — Kotaku — April 19, 2011
  228. 228NewsLet's Address Some Portal 2 NonsenseJohn Walker — April 19, 2011
  229. 229Portal 2 Metacritic user score poundedFred Dutton — Eurogamer — April 19, 2011
  230. 230Saling The World: Portal 2 Leads Cross-Platform Charts WorldwideDanny Cowen — Gamasutra — April 22, 2011
  231. 231Saling The World: Mortal Kombat Overtakes Portal 2 StatesideDanny Cowen — Gamasutra — April 29, 2011
  232. 232NPD: Mortal Kombat beats Portal 2 in USFred Dutton — Eurogamer — May 12, 2011
  233. 233NPD: May U.S. Retail Game Industry Sales Lowest Since Oct. '06Kris Graft — June 13, 2001
  234. 234Portal 2 Has Sold More Than 3 Million CopiesPatrick Klepek — Giant Bomb — June 22, 2011
  235. 235Portal 2 Scores Valve First Ever Top Spot In UK Sales ChartsMike Rose — Gamasutra — April 26, 2011
  236. 236Portal 2 Holds On To Top Spot For Second Week In UK Sales ChartsMike Rose — Gamasutra — May 3, 2011
  237. 237Analysis: Did The PSN Outage Hurt U.S. PS3 Hardware Sales?Matt Matthews — Gamasutra — June 21, 2011
  238. 238Developers Say PSN Outage Affecting Sales, But Remain HopefulKris Graft — Gamasutra — April 26, 2001
  239. 239Has PSN outage affected Portal 2 PS3 sales?Joe Anderson — ShopToNews — April 26, 2011
  240. 240Newell: Portal 2 Has Sold 3 Million CopiesKyle Orland — Gamasutra — June 22, 2011
  241. 241Crysis 2 racks up three million salesFred Dutton — Eurogamer — July 26, 2011
  242. 242The Valve Way: Gabe Newell And Erik Johnson SpeakChristian Nutt — Gamasutra — August 29, 2011
  243. 243Portal 2 has sold over 4M copiesEric Caoili — Gamasutra — May 8, 2012
  244. 244Portal 2 voted GOTY at Golden JoysticksMatthew Handrahan — GamesIndustry.biz — October 21, 2011
  245. 245MagazinePortal 2 – The Top 10 Everything of 2011 – TIMEDecember 7, 2011
  246. 246Gamasutra's Best Of 2011: Top 10 Games Of The YearGamasutra — December 23, 2011
  247. 247VideoIGNs 2011 Game of the Year VideoIGN — January 17, 2012
  248. 248Eurogamer's Game of the Year 2011Eurogamer — December 31, 2011
  249. 249Portal 2 Takes Kotaku's 2011 Game of the Year Award for Science, You MonsterMike Fahey — Kotaku — January 2, 2012
  250. 250News'Portal 2,' 'Skyrim' top a thrilling year in gamesDecember 21, 2011
  251. 251Portal 2, The Witcher 2 and Uncharted 3: Drake's Deception... the top 10 video games of 2011Kevin Lynch — December 23, 2011
  252. 252Portal 2 Leads Spike TV VGA Nominees With 12 NodsKyle Orland — Gamasutra — November 16, 2011
  253. 253MagazineSkyrim, Portal 2, Arkham City Won Big At VGAsJeff Cork — December 11, 2011
  254. 254Portal 2, Skyrim, Bastion lead finalists for 12th annual Game Developers Choice AwardsGamasutra — January 5, 2012
  255. 255Skyrim wins Game of the Year at GDC AwardsGamasutra — March 8, 2012
  256. 25615th Annual Interactive Achievement Awards FinalistsAcademy of Interactive Arts & Sciences — January 13, 2012
  257. 257MagazineSkyrim Dominates The 15th Annual Interactive Achievement AwardsMatt Bertz — February 9, 2012
  258. 258'Batman,' 'L.A. Noire' lead BAFTA game award nodsBrett Molina — February 16, 2012
  259. 259Portal 2 wins best game at the Bafta Video Game AwardsBBC — March 16, 2012
  260. 260Battlefield 3, Portal 2, more win big at 10th annual G.A.N.G. AwardsTom Curtis — Gamasutra — March 14, 2012
  261. 261Skyrim Wins Video Game Critics AwardSeth Schiesel — February 3, 2012
  262. 2622012 Golden Joystick Awards – Skyrim wins Ultimate Game of the YearStephany Nunneley — VG247 — October 26, 2012
  263. 263NewsValve reveals Steam Awards nominees
  264. 264The Steam Awards
  265. 2652010 WinnersGame Critics Awards
  266. 266Satelitte Awards 2011International Press Academy
  267. 267Valve details Teach with Portals, Steam for Schools educational initiativesDave Tach — Polygon — June 30, 2012
  268. 268How Portal 2 Developers Became The Best 6th Grade Physics Teachers EverKatie Salen — Fast Company — November 13, 2012
  269. 269Valve helps educators Teach With PortalsLeigh Alexander — Gamasutra — June 20, 2012
  270. 270Valve Gives Away Portal 2 for Free to Teachers with 'Steam for Schools'Evan Narcisse — Kotaku — June 20, 2012
  271. 271JournalCan we create a measure of fluid intelligence using Puzzle Creator within Portal 2?Cyrus K. Foroughi et al. — October 2016
  272. 272JournalThe power of play: The effects of Portal 2 and Lumosity on cognitive and noncognitive skillsValerie J. Shute et al. — August 2014
  273. 273JournalVideo games can develop graduate skills in higher education students: A randomised trialMatthew Barr — May 2017

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