Portal is a series of first person puzzle/platform game created by the Valve Corporation. The series takes place in the same universe as the Half-Life series, another one of Valve's games. The series' popularity has led to it having a large online fanbase.
The original title, Portal, was released on October 9th, 2007 on Microsoft Windows and Xbox 360, and subsequently on Playstation 3 on December 11, 2007 as part of the Orange Box package. It follows the story of Chell, a laboratory clone, who must complete all the test chambers in the abandoned Aperture Science Enrichment Center in order to escape. The challenges are set by the Center's rogue artificial intelligence GLaDOS. Because of the popularity of the original, Valve released a sequel, Portal 2, on April 19, 2011. Portal 2 had similar gameplay, and the plot focused more on the history of GLaDOS and Aperture Science. It also introduced a co-op campaign and a community-based map creation system.
Portal and Portal 2 received widespread critical and fan acclaim, and quickly became hugely popular. Both games won multiple Game of the Year awards in 2007 and 2011, respectively. Critics praised the games' innovative take on the more traditional first-person shooter. It was even argued by some that Portal is a "feminist critique" of modern FPS games; in the first title, the only two characters are Chell (the player) and GLaDOS (the antagonist), both of them women. GLaDOS appears as a giant robotic woman, bound and suspended by the ankles. These commenters have pointed to the Portal series as proof that not all women in video games have to be hypersexualized in order for the games to be marketable.
The Portal series has a large presence on 4chan /v/ board, and there are many other fansites. There has also been a large amount of fanart set in the Portal universe. As such, there are a number of deviantART groups and tumblrs. The interactions between Chell and GLaDOS are frequently depicted, and crossovers between Portal and other fandoms are very common. There have also been many Portal-related fan projects, including home-made portal guns, fan films, and even a video game crossover with the Super Mario series (Mari0).
One of the main focuses of the Portal fandom is the Weighted Companion Cube. In the first title, Chell encounters the Weighted Companion Cube at the start of one of the test chambers, and GLaDOS forces her to incinerate it at the end of the chamber. During the test, GLaDOS continually makes reference to how emotionally attached Chell is to the Cube. Thus, the Cube has become something of a fan icon of the series, with many pieces of official merchandise and fan-created memorabilia depicting it.
Thinking With Portals
Thinking with Portals is a catchphrase often accompanied by photoshopped images depicting how the concept of portals could be applied in real life. The phrase also serves as a synonym for the idiom "thinking outside the box".
The Weighted Companion Cube
The Weighted Companion Cube is a weighted storage cube in both Portal and Portal 2. It is distinguished from other weighted storage cubes in-game by the hearts displayed on its sides. In Portal, players must bring the cube where the weighted companion through an entire test chamber, only to throw it in an incinerator in the end. The idea was created from stories about isolated subjects falling in love with inanimate objects. As previously mentioned, GLaDOS repeatedly mentions the fact that the Weighted Companion Cube is the player's "only friend", etc. The cube has become so popular that Valve began to sell plushie cubes, and it features heavily in fanart.
The Cake is a Lie
The Cake is a Lie is widely popular catchphrase used originally by Portal players, but soon it spread to forums and blogs where the phrase began to take on a new meaning outside of the context of the game. Originally, it was intended to express disappointment with the fact that the cake GLaDOS promises to serve Chell when she completes the test chambers appears to be nonexistent, replaced instead by a furnace. The phrase has generally come to refer to "carrot-and-stick" scenarios, in which a prize is held just out of reach in order to motivate the subject.
Still Alive (Portal End Theme)
Still Alive is the song that plays during the end credits of Portal. It was composed by Jonathan Coulton and performed by Ellen McLain, the actress who voiced GLaDOS. The song became immensely popular, and has spawned many tributes and covers on YouTube, as well as a number of YTMND sites.
I'm a Potato
"I'm a Potato" is a catchphrase spoken by GLaDOS in Portal 2, when she gets her artificial intelligence implanted into a potato, much to her chagrin. The exact phrase, "How are you holding up? Because I'm a potato." is frequently used to force someone to take perspective of their problems, and realize that they aren't as bad as they seem.
Cave Johnson / Combustible Lemons
Cave Johnson and Combustible Lemons are a pair of memes originating in Portal 2. The founder and CEO of Aperture Science, Cave Johnson, makes an in-game speech about lemons, and how "if life gives you lemons, [you should use them to] make grenades." Since the game’s release, both Cave Johnson and his speech about combustible lemons have been the subject of various image macros and video remixes.
The Space Personality Core is a robot AI character at the end of Portal 2. The robot has been programmed to be obsessed with space, and constantly repeats the word “space”. It also lists facts about space, and reflects on what it will do once it gets to space. It's often quoted saying “Spaaaaaaacce”, and has inspired several single serving sites.
Get the Cake
Get the Cake is a rage comic-based satirical take on the Portal series. Get the Cake appears to have originated on 4chan in 2007. The image macro typically shows an insurmountable obstacle between "you" and the cake, typically a spike-covered opening. It is often combined with troll physics to show how to beat the obstacles.