Portal 2 is a puzzle-platform game released in 2011. Valve created it for Windows, macOS, Linux, PlayStation 3, and Xbox 360. The digital PC versions are sold online through Valve’s Steam service, while store versions are sold by Electronic Arts. A version for the Nintendo Switch was released in June 2022 as part of the Portal: Companion Collection.
Like the original Portal (2007), players solve puzzles by placing portals and moving between them. Portal 2 includes new features such as excursion funnels (called tractor beams in files), lasers, light bridges, and paint-like gels that change movement or allow portals to be placed on any surface. In the single-player story, players control Chell, who moves through the damaged Aperture Science Enrichment Center during its rebuilding by the supercomputer GLaDOS (Ellen McLain). New characters include robot Wheatley (Stephen Merchant) and Aperture founder Cave Johnson (J. K. Simmons). In the cooperative mode, players work together as robots Atlas and P-Body (both voiced by Dee Bradley Baker). Jonathan Coulton and the National created songs for the game.
Valve announced Portal 2 in March 2010 and promoted it with alternate reality games, such as the Potato Sack, which involved other game developers. After its release, Valve added downloadable content and a simple map editor to let players create and share levels.
Portal 2 received praise for its gameplay, smooth difficulty, pacing, humor, writing, and acting. Like its predecessor, many publications and critics have called it one of the greatest video games ever made.
Gameplay
Portal 2 is a puzzle game played from the player's viewpoint. In the single-player campaign, the player controls a character named Chell. In the cooperative campaign, the player controls one of two robots—ATLAS or P-Body. In community-made puzzles, the player uses a simple human-like figure. Characters can survive some damage but will die if hurt for too long. The goal of both campaigns is to explore the Aperture Science Laboratory, a complex, changeable maze of machines. Some parts of the game take place in test chambers with clear entrances and exits, while other parts occur in hidden areas where the goals are less obvious.
The game begins with tutorials that teach movement and how to interact with the environment. In the cooperative campaign, players also learn how to work with another player. Gameplay involves using the Aperture Science Handheld Portal Device, which creates two portals on surfaces. Players can use these portals to move between rooms or launch themselves or objects across distances.
New elements in Portal 2 include Thermal Discouragement Beams (laser beams), Excursion Funnels (tractor beams), and Hard Light Bridges, all of which can pass through portals. Aerial Faith Plates launch players and objects through the air. Players must avoid or disable dangerous turrets. The Weighted Storage Cube has been redesigned, with new versions like Redirection Cubes (which change laser directions), Edgeless Safety Cubes (an older type used in hidden areas), and a cube-turret hybrid made by Wheatley. A heart-decorated Weighted Companion Cube appears briefly. Early versions of the game included Pneumatic Diversity Vents, but these were removed in the final version. The goal of each test chamber or level is to use the portal gun and game tools to unlock doors and move forward.
Paint-like gels, which are released from pipes and can pass through portals, give surfaces or objects special abilities. Orange Propulsion Gel helps players move faster across surfaces, blue Repulsion Gel allows players to bounce off surfaces, and white Conversion Gel lets surfaces accept portals. Only one type of gel can affect a surface at a time. Some surfaces, like grilles, cannot be coated with gels. Water can remove gels, returning surfaces or objects to their normal state.
In the cooperative campaign, two players can use the same console with a split screen or separate devices. Players on Windows, Mac OS X, or PlayStation 3 can play together regardless of their platform. Both players control robots with their own portal guns, and portals created by either player can be used by both. Most chambers require teamwork, such as using both players’ portals to redirect lasers or launch objects. The game includes voice communication, and online players can temporarily view a split-screen to coordinate actions. Players can "ping" to alert others, set countdowns for synchronized actions, or perform gestures like waving or hugging. The game tracks completed chambers and allows players to replay them with new partners.
Portal 2’s lead writer, Erik Wolpaw, estimates each campaign takes about six hours to complete. The game includes in-game commentary from developers, writers, and artists, unlocked after completing chapters. According to Valve, each campaign is 2 to 2.5 times longer than the original Portal, and the entire game is five times longer than the original.
Synopsis
The Portal series and the Half-Life series take place in the same fictional universe. The events in Portal happen between the first and second Half-Life games. Most of Portal 2 takes place "a long time after" the events in Portal.
Before Portal, Aperture Science tested whether humans could safely move through dangerous rooms. The artificial intelligence named GLaDOS controlled the laboratory and killed its workers. At the end of Portal, the main character, Chell, destroys GLaDOS and escapes the facility briefly. Later, she is pulled back inside by a mysterious figure, later identified as the "Party Escort Bot." A promotional comic shows Doug Rattmann, a former Aperture employee, who used graffiti to guide Chell. He placed her in suspended animation to save her life until the start of Portal 2.
In the Aperture Science Enrichment Center, Chell wakes up in a stasis chamber that looks like a motel room. The facility has fallen into disrepair after many years of decay. Wheatley, a personality core, helps Chell navigate old test chambers to escape after the facility loses power. While trying to restore power, they accidentally wake up GLaDOS, who separates Chell from Wheatley and begins rebuilding the facility.
GLaDOS forces Chell to take new tests until Wheatley helps her escape again. Together, they stop Aperture from making weapons and harmful substances to protect themselves. They confront GLaDOS and replace her with Wheatley as the facility’s controller. Wheatley becomes unstable with power and installs GLaDOS on a potato battery. GLaDOS explains that Wheatley was designed to make her think less clearly. Wheatley then accidentally destroys the elevator to the surface, trapping Chell and GLaDOS in the lowest part of the facility.
Chell retrieves GLaDOS from the potato battery, and they work together to stop Wheatley from destroying the facility. They travel through 20th-century laboratories and find audio recordings by Aperture’s founder, Cave Johnson. The recordings show how Aperture lost money and reputation over time. In 1981, Johnson became seriously ill after using moon dust to create portal surfaces. His final wish was to transfer his assistant’s mind into a computer, which became GLaDOS. GLaDOS learns she was once named Caroline.
Chell and GLaDOS return to the facility’s upper levels and find that Wheatley’s mistakes have nearly destroyed the facility. Wheatley decides to keep Chell and GLaDOS as test subjects because his robots failed to solve puzzles. GLaDOS explains that she feels happy when completing tests, but this feeling weakens over time. Wheatley grows frustrated as the happiness from tests decreases.
Wheatley tricks Chell and GLaDOS into a trap, claiming he no longer needs Chell after discovering the robots from the cooperative campaign. Chell escapes just before the trap activates. The final levels involve escaping Wheatley’s attempts to kill them.
In the final battle, Chell forces a core transfer to restore GLaDOS’s control, but Wheatley breaks the button needed for the transfer. As the facility collapses, Chell creates a portal to the Moon, pulling herself and Wheatley into space. GLaDOS rescues Chell and leaves Wheatley in space. After waking up, GLaDOS deletes Caroline’s personality and lets Chell leave the facility.
The cooperative story happens after the main campaign but does not require playing in order. The robots Atlas and P-Body are created by GLaDOS to complete missions in the facility. After each mission, they are disassembled and rebuilt for the next task.
At first, GLaDOS is excited about testing robots, but she becomes upset because they cannot die and because they work well together. At the end of the story, the robots find "the Vault," a storage area for humans in suspended animation. GLaDOS thanks them for finding new test subjects and destroys the robots.
One week later, GLaDOS reactivates the robots to find a saboteur causing problems. The saboteur is a bird pecking at a keyboard. GLaDOS panics when she recognizes the bird as the one that tried to eat her earlier. The robots scare the bird away, earning a rare compliment from GLaDOS. She then takes the bird’s eggs to raise baby birds as her killing machines.
Development
After the success of Portal, Valve decided to make Portal 2 a standalone game. This decision was partly due to other developers at Valve who wanted to work on a Portal project. Work on Portal 2 began soon after Portal was released. Valve used more resources for Portal 2 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 original team of four grew as smaller groups formed to create game mechanics and plan the story. People who reviewed the project were inspired to join because of what they saw. According to Erik Wolpaw, some Portal 2 developers worked on Left 4 Dead to meet deadlines but returned to Portal 2 with extra help. Kim Swift, the designer of Portal, left Valve for Airtight Games halfway through Portal 2’s development.
Project manager Erik Johnson said Valve’s goal for Portal 2 was to “re-surprise” players, which he called a “terrifying” challenge. 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 was released, Geoff Keighley reported that Newell said Portal 2 might be Valve’s last game with a single-player experience. Keighley noted that the word “probably” suggests this might change. Newell said Valve is not giving up on single-player games but plans to add more social features, like the cooperative mode in Portal 2.
Initially, Valve planned to exclude portals from a Portal sequel. For five months, they focused on a gameplay idea called “F-Stop.” Valve did not share details about this idea because they might reuse it later. In 2020, developer LunchHouse Software revealed they used Valve’s F-Stop code in their game Exposure. The mechanic involved an “Aperture Camera” that let users take photos of objects, store them, and replace them while rotating or scaling them. Valve’s F-Stop game was set in the 1980s and would not have included Chell or GLaDOS. Instead, it followed a new test subject involved in a conflict at Aperture after Johnson, trying to achieve immortality, uploaded himself into an AI and controlled a robot army. Though playtesters liked F-Stop, they were disappointed portals were not included. Based on feedback, Newell told the team to reconsider their direction around October 2008.
Valve did not aim to make Portal 2 harder than Portal, but wanted to create a game where players could solve puzzles and feel smart. To teach players gradually, Valve designed two types of test chambers: one provided a safe space to experiment with new ideas, and the other combined elements to challenge players to think creatively.
Test chambers started as drawings on whiteboards. Developers checked if the ideas made sense before creating simple levels with Hammer Editor, Valve’s level-building tool. Playtesting ensured puzzles were neither too easy nor too hard. Sometimes, playtesters found alternative solutions, which the team removed if they were too simple.
Valve wanted to teach new players about portals while still entertaining experienced players. They simplified some elements, like replacing moving energy balls in Portal with lasers that give immediate feedback. To show time had passed, Valve included test chambers from the original Portal with higher-resolution textures and effects like decay and overgrowth.
The middle part of the single-player story takes place in large spaces with few portals, forcing players to find creative ways to move. The design was inspired by photos of places like CERN, NASA, and the Soviet space program. When Wheatley controls Aperture, the designers created chaotic rooms reflecting his character’s mistakes. To avoid tiring players, the team added “experiences” to break up puzzle-solving and advance the story.
The Repulsion (jumping) and Propulsion (running) gels in Portal 2 came from the game Tag: The Power of Paint. Valve hired the Tag creators to develop the idea further and later added it to Portal 2. Journalists compared Tag to Narbacular Drop, a student project that inspired Portal. A third Tag gel, which let players walk on any surface, caused motion sickness and was replaced by Conversion gel, which works with portals. Gels gave players more control over the environment, making puzzles harder for designers. Valve used special computer programs developed by the Tag team to render gels and techniques from Left 4 Dead 2 to make water effects realistic.
The cooperative mode came from players’ requests and stories of people solving puzzles together on the same computer or console. Erik Wolpaw compared this to working on point-and-click adventure games together. The cooperative campaign was also inspired by Left 4 Dead, where players discussed their experiences after finishing the game.
While the single-player story avoids frustrating players, cooperative levels focus on teamwork and communication. Valve admits cooperative puzzles are harder than single-player ones. They did not include timed puzzles in Portal or Portal 2’s single-player campaigns but found timed puzzles in cooperative mode helped players feel accomplished after solving challenges.
Each cooperative puzzle requires both players to act. If a playtester found a way to solve a puzzle with one set of portals, the level was redesigned. Most chambers kept players in sight to encourage teamwork. Some puzzles were designed asymmetrically, with one player controlling portals to help the other cross the room. Designers later added instructional icons to help players communicate better than using verbal instructions.
Valve considered a competitive mode similar to the game Speedball, where teams used portals to move a ball across a field. However, matches became too chaotic, and Valve focused on cooperative mode instead because players enjoyed solving puzzles together.
Marketing and release
In January 2008, Valve representative Doug Lombardi told Eurogamer, "There will be more Portal, for sure," and Portal designer Kim Swift confirmed that work on Portal 2 would begin the following month. Swift said that a multiplayer mode in Portal was "technically possible," but that it was "less fun than you'd think."
Portal 2 was officially announced on March 5, 2010, by Game Informer. Events in the week before the announcement gave clues about the release. On March 1, 2010, Valve released a patch for Portal that included a new achievement called "Transmission Received," which required players to use in-game radios. This revealed new sound effects that became part of an alternate reality game (ARG). Some of the effects were Morse code messages suggesting GLaDOS was rebooting, while others could be decoded as images from grainy Aperture Science videos. These images included hints to a BBS phone number. When accessed, the number provided many ASCII-based images related to Portal and parts of Aperture Science documents. Many of these images were later shown in the Game Informer announcement. More ASCII images continued to appear on the BBS after the official release. Background about the ARG is included in additional SSTV images found in a hidden room in Portal 2. Adam Foster from Valve created the ARG idea, linking it to the Game Informer announcement. He used his home phone line to run the BBS software because Valve’s offices at the time did not support the protocol. Foster estimated the ARG cost less than $100 to run.
A second patch for Portal, released on March 3, 2010, changed the game’s ending to show Chell being pulled back into the Aperture facility. Gaming journalists guessed that an announcement for Portal 2 was coming soon. On March 5, Game Informer announced Portal 2’s official release on the cover of its April issue. During the following week, 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 screen showed a message supposedly from GLaDOS, hinting at more Portal 2 news at E3 2010. Two weeks before E3, journalists received a cryptic email written as a press release from Aperture Science, suggesting that the Portal 2 presentation would be replaced with "a surprise" hosted by Aperture Science and Valve. This led to guesses that the surprise might be the announcement of Half-Life 2: Episode Three. However, Valve confirmed it would be about Portal 2. The surprise was the announcement of Portal 2 for PlayStation 3.
On April 1, 2011, Valve released another alternate reality game called the Potato Sack. Players worked together online to solve puzzles. Some journalists thought the game indicated Portal 2 would be released on April 15, 2011, instead of the planned date of April 19. On April 15, players discovered "GLaDOS@Home," a spoof of distributed computing that encouraged participants to play games to unlock Portal 2 early. After solving the puzzles, Portal 2 was unlocked on April 18 at around 21:30 PST, about ten hours before its planned release on April 19 at 7:00 PST.
Valve created television commercials to promote Portal 2. In the past, Valve had worked with advertising agencies, but Doug Lombardi was unhappy with earlier ads, calling them "Copycat treatments. Cliché treatments. Treatments that reveal the agency wasn’t listening in the initial meeting." Using viewer feedback, Valve adjusted the ad content until they were satisfied. The ads took eight weeks to complete. Valve also made online videos with J. K. Simmons narrating as Cave Johnson to promote new gameplay features in Portal 2. These videos were part of a larger effort described by Newell as a "documentary-style investment opportunity" for Portal 2. A video released on February 14, 2011, promoted the cooperative aspect of Portal 2 as a St. Valentine’s gift and increased preorder interest. Lombardi said the videos had a greater impact than demos and interviews. Valve also sold Portal 2-themed merchandise, such as posters, drinking glasses, and T-shirts.
The March 2010 announcement said Portal 2 would be released in late 2010. In August 2010, Valve postponed the release to February 2011, with a Steam release date of February 9, to allow time to improve the game’s dialogue, fill and connect about sixty test chambers, and refine the gel gameplay mechanic. Valve announced another delay in November 2010, setting a retail release date for the week of April 18, 2011: April 20 in North America and April 22 in Europe and Australia. Wolpaw said the eight-week delay was used to expand the game’s content before reaching an internal milestone called a "content lock," after which no more content could be added. The remaining work focused on debugging. Newell approved the delay because he believed the added content would not hurt sales. On February 18, 2011, Newell confirmed that development on Portal 2 was complete and that the team was waiting for final approvals and disc manufacturing. Portal 2 was the first Valve product released simultaneously for Windows and Mac OS X through Steam. Retail copies for all platforms were distributed by Electronic Arts.
The Xbox 360 version of Portal 2 was added to the Xbox One’s backward compatibility feature in June 2016. Alongside Portal, Portal 2 was released on the Nintendo Switch on June 28, 2022, as part of the Portal: Companion Collection, developed by Valve and Nvidia Lightspeed Studios.
Hardware support
Sixense created a version of Portal 2 that works with the Razer Hydra motion controller for PC, allowing players to control game elements more precisely. This version includes ten extra single-player levels available as downloadable content. Writer Chet Faliszek stated that Sixense developers worked for nine months to a year at Valve’s headquarters to create the PC-specific version. A special edition of the Razer Hydra includes a copy of Portal 2 for PC.
The news that Portal 2 would be released on PlayStation 3 surprised the gaming industry because Gabe Newell, a leader at Valve, had previously criticized the console. He mentioned challenges during the port of The Orange Box to PlayStation 3. The decision to release Portal 2 on PlayStation 3 came from frustration with Microsoft’s rules for Xbox 360 content, such as the difficulty of sharing updates and new content. Newell believed Sony’s system for publishing games was more open, allowing features similar to Steam to be used on PlayStation 3. Portal 2 was the first PlayStation 3 game to use some Steamworks features, such as automatic updates, downloadable content, and community support. The game allowed players to play with others on PlayStation 3, Windows, and OS X versions. PlayStation 3 cross-play ended in 2016, but cross-play between PC, Mac, and Linux versions remains available.
The Steam overlay displays a player’s friends from both Steam and PlayStation Network, and achievements are given for both Steam and PlayStation Network Trophies. Players can unlock Portal 2 on Steam for Windows and OS X without extra cost. Using Steamworks on PlayStation 3 lets Valve track problems after the game is released and send updates. Valve has said it does not plan to add other PlayStation 3 features, such as 3D television or PlayStation Move support. In June 2012, Valve announced that the PlayStation 3 version would later include support for the PlayStation Move motion controller and add content previously available with the Razer Hydra, called Portal 2 In Motion. This update was released in November 2012. A free co-op add-on for Portal 2 In Motion was added in June 2013. Valve confirmed that despite extra support for PlayStation 3 compared to Xbox 360, the main game is the same on both platforms.
Since February 2014, SteamOS, Valve’s Linux-based operating system, has supported Portal 2 and its earlier version. Most modern Debian-based Linux distributions also support the game through the Steam client. Released as a Beta in early 2014 for Linux users, SteamOS includes the same features as other versions, such as cross-platform play, split-screen mode, and full support for controllers.
Additional content
Portal 2 includes extra content, such as four promotional videos, a comic called "Lab Rat," and an interactive trailer for the 2011 movie Super 8. This trailer was made using the Source game engine. A feature called "Robot Enrichment" lets players change the characters in the cooperative campaign by adding new gestures and items like hats or flags. These items can be earned through gameplay, traded with other players, or purchased using in-game money.
Valve planned to release downloadable content for Portal 2, starting with Peer Review, which came out on October 4, 2011. This content is free for all platforms and adds a new cooperative campaign that continues the game's story. Near the end of this campaign, GLaDOS prepares Atlas and P-Body to deal with an intruder in Aperture Science—a bird that had previously taken GLaDOS as a potato. The content also includes a "challenge mode," similar to the one in Portal, where players race to complete test chambers in the shortest time or with the fewest portals. These challenges are tracked on leaderboards for both single-player and cooperative play.
As of January 2013, Valve supported fan use of Portal 2 content by sharing selected game assets and providing help. The Windows version of Bastion includes a weapon inspired by Portal 2’s Conversion Gel and turrets. Its developer, Supergiant Games, received writing help from Erik Wolpaw, and Ellen McLain voiced new lines for the turrets. An add-on for Defense Grid: The Awakening includes GLaDOS as an antagonist with new dialogue and assets from Portal 2. Wolpaw and McLain also helped create new lines for GLaDOS in a custom map used by Gary Hudston to propose marriage. Valve created a free add-on for The Elder Scrolls V: Skyrim to support Steam Workshop content, introducing the Space Core as a character that follows the player. Valve also worked with Zen Studios to make a Portal 2-themed pinball table for their games Pinball FX 2 and Zen Pinball. A Portal 2-themed set is available in Lego Dimensions, featuring stories written by Traveller’s Tales with Valve’s approval, and includes voice roles from Ellen McLain, Stephen Merchant, and J.K. Simmons. A new GLaDOS credits song was written by Jonathan Coulton and performed by McLain.
According to Faliszek, user-created content for Portal 2 would be available on all platforms, but modding tools would only work on Windows due to software limits. Valve released beta versions of these tools on May 10, 2011, and supported a competition on the website "Thinking with Portals" in May 2011, offering prizes for popular maps. The "Perpetual Testing Initiative," a free update for Windows and Mac versions, was released on May 8, 2012. It included a new level editor and a way to share user-made levels through Steam Workshop. In November 2011, Geoff Keighley of GTTV said Valve was working on a simpler level editor for beginners and an in-game system to share maps via Steam Workshop. This system entered beta testing in March 2012. Within days of release, the Perpetual Testing Initiative had helped create 35,000 maps, with 1.3 million downloads. Within a month, over 150,000 user-made maps were available. The first version of the update only allowed single-player maps, but a patch in August 2012 let users make cooperative maps.
In addition to user-made levels, complete mods of Portal 2 have been created. Some mods are self-contained campaigns that have received praise. Thinking with Time Machine is a single-player mod made by Ruslan Rybka and released in 2014. It lets players record actions that a copy of the player can repeat, including using a second set of portals. Aperture Tag: The Paint Gun Testing Initiative is a mod by "The Aperture Tag Team" released in 2014. It replaces the portal gun with a paint gun that uses gels to solve puzzles. Portal Stories: Mel is a mod by Prism Studios, released on June 25, 2015, for Windows, OS X, and Linux. It is free for people who own Portal 2 on Steam. Portal Reloaded is a mod by Jannis Brinkmann, released on April 19, 2021, exactly 10 years after Portal 2’s launch. It adds a "time portal" that lets players move between the present and future versions of test chambers. Portal: Revolution is a mod by Second Face Software, released on January 6, 2024.
Reception
Portal 2 was very popular with gaming journalists during secret previews at the E3 2010 event. The Game Critics Awards, chosen by journalists and critics, gave Portal 2 the titles of Best PC Game and Best Action/Adventure Game. The game was also nominated for Best of Show and Best Console Game. IGN named Portal 2 the best game at E3 for PC, Xbox 360, and PlayStation 3 systems, as well as Best Puzzle Game. It was also nominated for Best Overall Game. GameSpy named Portal 2 the Best Overall Game and Best Puzzle Game at E3. Portal 2 won the 2010 Spike Video Game Award for "Most Anticipated Game for 2011."
When Portal 2 was released, it received very good reviews. Many reviewers said it was a strong contender for "Game of the Year," and some called it one of the best games ever made. Many believed it was as good as or better than the original Portal game. Eurogamer’s Oli Welsh said the game avoided common problems in sequels, writing that "Portal is perfect. Portal 2 is not. It’s something better than that." Gus Mastrapa of The A.V. Club said Valve showed that Portal could be expanded into a big, story-rich game with all the features of a mainstream hit. IGN’s Charles Onyett said the sequel made the original look like a prototype by improving gameplay and story.
Most reviewers praised the writing and voice acting in the game. Dan Stapleton of PC Gamer predicted many plot twists in Portal 2’s story but still enjoyed seeing how characters reacted. He said the characters’ charm made the game world feel lively. Onyett wrote that Merchant’s enthusiasm helped the game and that the writing was clever and matched the action well. Adam Biessener of Game Informer said Johnson was an even better character than GLaDOS and praised the game’s "pitch-perfect delivery" and "brilliant comedic timing." Peter Bright of Ars Technica said the characters, Wheatley and GLaDOS, made the game feel less lonely and sad than the first game, and the dialogue sometimes disrupted the mood.
New gameplay elements like light bridges, lasers, and gels were praised as good additions. Reviewers liked the puzzles, which looked complex but had simple solutions. Evan Narcisse of Time said he worried new elements might make the game less pure but said Valve kept its charm. Tom Hoggins of The Telegraph said the game taught players through clever design instead of direct instructions. Chris Kohler of Wired said the puzzles never needed overly complicated solutions and often made players feel proud when they solved them. Stapleton said the gels were harder to control and had limited uses. Bright said Portal 2 was easier than the first game, as much of it felt like tutorials for new mechanics.
The cooperative puzzle-solving mode was praised as a great addition. Oli Welsh said the co-op mode was one of the most satisfying ways to play with a friend. Onyett said Valve designed the mode so that teamwork was essential for success. Reviewers liked the non-verbal cues players could use to work with partners. The game’s design, sound, and music were also praised for their detail. Nelson said the game’s world felt real and natural. Onyett said the game’s visuals and animations helped players understand the characters better. Hoggins said the game’s world reacted to the player in a natural way and compared Valve’s design to the world-building in BioShock.
Some reviewers said the second part of the game, set in older Aperture facilities, might be confusing. Young said the difficulty increased quickly, which might frustrate casual players. Kohler said the abandoned areas of Aperture felt lifeless and uninteractive. Watters said the loading times between levels were longer than in earlier Valve games. He also said the lack of test chambers and leaderboards was a downside, though he said the game still had enough content. Welsh said the attempt to recreate the song "Still Alive" in the credits was a mistake. Ben "Yahtzee" Croshaw said Portal 2 changed parts of the original game’s story unnecessarily but praised the co-op mode.
On April 20, 2011, some customers complained about Portal 2. They said the game was too short, had downloadable content for some versions, and that the Windows and Mac versions were ports of the console game. Some journalists said the graphics on Windows and Mac versions looked high quality, not like simple ports. Stephen Totilo of Kotaku said the game lasted nine hours and that downloadable content only added cosmetic items. Some said the early release of the game might have affected user scores.
According to Amazon.com sales data, Portal 2 was the best-selling game in the U.S. during its first week. It was overtaken by Mortal Kombat in the second week. NPD Group reported that Portal 2 was the second-best-selling game in the U.S. in April 2011, with 637,000 copies sold, and the fourth-best-selling in May. However, NPD does not include sales from Valve’s Steam platform. Portal 2 was the best-selling game in the U.K. during its first week.
Educational use
In June 2012, Valve introduced two programs called "Teach with Portals" and "Steam for Schools." These programs provided free access to the video game Portal 2 and its Puzzle Maker tool for educational purposes. The free version included only the single-player story mode and the Puzzle Maker, and it was available only to users of "Steam for Schools."
Many critics praised Portal 2 for helping players learn how to solve puzzles. In a review for the New York Times, Seth Schiesel wrote that a creative high school physics teacher might use Portal 2 as a key part of science lessons, greatly benefiting students. Teachers of math and science sent emails to Valve explaining how they had used Portal 2 in their classrooms to support the idea of using games to teach students.
Portal 2's developers, Joshua Weier and Yasser Malaika, worked with a team at Valve to find ways to use the game in education. This effort led to the creation of Puzzle Maker, a tool that allowed players to design their own puzzles. Puzzle Maker was built using the same tools used to create the game. Weier and Malaika focused on giving teachers tools to create lessons, rather than designing lessons themselves. Before Puzzle Maker was released in 2012, a tool called Hammer was the only option available, but it was hard for teachers to use. To help, Valve made Puzzle Maker easy to learn and allowed users to share puzzles and lesson plans. The tool was developed with the help of a math teacher and her students. This work led to the launch of the "Steam for Schools" program in June 2012, which allowed educators to get Portal 2 and Puzzle Maker for free for classroom use. By November 2012, Valve reported that more than 2,500 teachers were using the "Teach with Portals" program in their lessons.
In 2016, a study showed that the Portal 2 Puzzle Maker could be used to measure problem-solving skills, similar to a test called the Bochumer Matrices Test (BOMAT). This test, called the Portal 2 Test Battery, required participants to complete increasingly difficult puzzle challenges.
Other studies have explored whether video games can improve skills like thinking, problem-solving, and perseverance. A 2014 study found that playing Portal 2 helped improve problem-solving, spatial thinking, and persistence, even for people who had never played games before. A 2017 study also found that games like Portal 2 could help improve communication, adaptability, and the ability to find creative solutions.