Portal storyline

This article describes the Portal storyline, chapter by chapter.

Portal is set in the Half-Life universe, and is presented to the player through the game's audio messages and visual elements seen throughout the game. Additional elements of the story's background are developed from the fictional Aperture Science website created by Valve for the game.

Testchamber 00


Chell wakes up in a so-called Relaxation Vault - with only a small table with a mug, radio, and clipboard listing test chamber hazards, as well as a toilet and a stasis bed of some kind- and is welcomed "again" by a Computerized Voice, that states that "her specimen has been been processed" and that "we are now ready to begin the test proper."

Chell then proceed through the first area, and is introduced to Buttons, Cubes, and the Vital Apparatus Vents, as well as the Material Emancipation Grids.

Throughout the early stages of the game, GLaDOS only refers to "us" or "we," never saying "I," as though she were speaking for the Enrichment Center's long gone employees as a whole. This come into significance in the later levels, when she begins acting as an independent entity.

Trivia

 * The radio inside of Chell's chamber plays an instrumental version of "Still Alive".

Behind the scenes

 * The portal was deliberately introduced in this stage in a way that confirms that they lead to another location on the same planet, rather than another universe, as established in Developer Commentary.

Test Chamber 01


Here the player reviews how to use buttons, storage cubes, and portals.

Behind the scenes
This level is designed to firmly establish the mechanics of the Portal Device in the player's mind, so that they would be familiar with the basic concept of the game.

Test Chamber 02


As the tests progress she eventually acquires the first "portion" of the Aperture Science Handheld Portal Device, allowing her to place blue portals but not orange ones.

Test Chamber 03


A simple puzzle using the newly acquired portal gun.

Behind the scenes
This level was intentionally designed to ensure players realize that both portals can be used as entrances and exits.

Test Chamber 04


More buttons and boxes.

Test Chamber 05


This time, there are two boxes and two buttons. GLaDOS reveals that "our previous statement suggesting that we would not monitor this chamber was an outright fabrication." This begins to hint at her malicious behavior. She then states says that "We will stop enhancing the truth, in 3, 2 -" but is cut off before she can finish, effectively nullifying the statement.

Test Chamber 06


Here, the Aperture Science High Energy Pellet is introduced.

Test Chamber 07


More energy balls, also moving platforms are introduced.

Test Chamber 08


Acid pits are introduced, in combination with moving platforms and energy balls.

Test Chamber 09


A so called "impossible" test chamber, with buttons and cubes used.

Trivia
Later in the game, this chamber is revisited illicitly, and must be solved in a different way, as the cube is no longer available.

Test Chamber 10


A new concept is introduced: flinging. As GLaDOS says: "Momentum, a function of mass and velocity, is conserved between portals. In layman's terms, speedy thing goes in, speedy thing comes out."

Test Chamber 11


Chell acquires an upgrade that allows her to place orange portals.

Test Chamber 12


More flinging, now with more freedom allowed by the upgraded device.

Test Chamber 13


The first real challenge. Combines buttons, boxes, energy balls and moving platforms.

Behind the scenes
The previous stages were constructed to introduce the basic concepts of Portal in small, easily-understood segments, and this stage collects them into one place as a sort of 'final review'.

Test Chamber 14


Another challenge. Combines buttons, boxes, energy balls, moving platforms (moving vertically in this case) and acid pits.

Test Chamber 15


A very long chamber with all of the above included.

Test Chamber 16
"Due to mandatory scheduled maintenance, the appropriate chamber for this testing sequence is currently unavailable. It has been replaced with a live-fire course designed for military androids. The enrichment center apologizes for the inconvenience and wishes you the best of luck."

This level introduces turrets, three foot tall gun-toting tripods that speak cute phrases when they see a target or are tipped over.

The player finds the first Ratman den, hinting at the reality of the tests, as well as the fact there there are other people still trapped in the building..

Test Chamber 17
Notable because of the appearance of another character: the companion cube. At the end of the chamber, Chell is forced to "euthanize," or more bluntly, incinerate the Companion Cube.

Behind the scenes
This chamber was actually originally a long level called the "cube run," where players would take the cube through a number of challenges. However, playtesters would leave the cube behind, so they put a heart on it and had the AI keep on talking about it.

Test Chamber 18


By far the hardest chamber. Turrets reappear here. At the end, GLaDOS says that "the next test requires exposure to uninsulated electrical parts, that may be dangerous under certain conditions," which comes into importance later.

Test Chamber 19
The last chamber. A simple energy ball trick is required, followed by a time-limited sequence on a moving platform.

As the platform rounds a corner, awaiting the player is not the long-awaited cake but a large incinerator. Chell escapes via portals, much to GLaDOS's apparent displeasure; she briefly babbles electronically. She stutters on her "I," revealing her true nature, before regaining control and attempting, unsuccessfully, to convince Chell that this was "the final test, where we pretended we were going to murder you." Chell escapes into the bowels of the Enrichment Center.

Escape
After the final test, Chell is "sent to receive her cake", but is plunged into a furnace (to "be baked," as GLaDOS had accidentally admitted numerous previous times, with glitches resembling Freudian slips). She manages to escape into a maintenance area and GLaDOS begins to show agitation, claiming first that it was the real final test, and then that it was just a joke. She tells Chell that there will be a party held in her honor and urges her to "assume the party-escort submission position" on the floor. Chell flees into the facility's numerous maintenance areas, and GLaDOS becomes increasingly agitated. Roughly the second half of the game continues behind the walls of previous stages and the inner laboratories of Aperture Labs as Chell follows eerie notes written on walls and uses the Portal Gun to work her way through the facility. Finally, Chell confronts GLaDOS, a large machine hanging in a cylindrical shaft. (Near the entrance to the room is a desk with a red phone. The developers stated that there was someone stationed at the red phone in case GLaDOS showed signs of independent thought; apparently, they weren't able to make the call, as the wires were cut.) As Chell destroys critical components of the machine, GLaDOS's personality degenerates. During this confrontation, GLaDOS makes several comments that something has gone wrong in the outside world, and that she is the only thing keeping the facility from "them", possibly the Combine, or something else entirely. After Chell destroys the last component, some form of portal opens above them, tearing apart GLaDOS and sucking in Chell. Chell wakes up at the Enrichment Center's gate, among the wreckage of GLaDOS, as debris rains down from the massive, unseen portal. Then the Party Escort Bot thanks Chell for assuming the party escort submission position, and brings her back inside the facility.

The final cutscene zooms up and through various areas of the Enrichment Center, ending in a darkened room showing the promised cake surrounded by various metallic glowing orange spheres similar to those that were installed in GLaDOS. Some of the eyes activate and a robotic arm puts the candle out. The credits roll as GLaDOS gives a concluding report about Chell in the form of the song "Still Alive" by Jonathan Coulton. It reveals that GLaDOS enjoys the companionship of the test subjects and that it felt a particular fondness for Chell. The song seems to hint that GLaDOS is, indeed, still alive.

When the credits and song end, the player is greeted with a new background: a cake with lit candles on a desk next to a radio on a table as well as the same red phone (which has its buttons shaped like the Aperture logo). If the background is left alone for long enough, it eventually pans to show the Companion Cube on the floor to the right side of the desk.

Trivia

 * This section of the game does not bear any official title. "Escape" is the map prefix, and the game files refer to "Behind the Scenes," or "BTS". Within the game itself it's listed as part of Test Chamber 19.