Story

The Portal games are story driven games, as such the scenario takes an important place in the gaming experience.

In the games you play Chell, a young women stuck in an Aperture Science complex forced by the Artificial Intelligence GLaDOS to solve tests in specialy designed chambers using for solving them the Handheld Portal Device.

Portal
The game has two distinct acts, the test chambers and the escape.

Act 1: The test chambers
The game begins with the player awakening in a Relaxation Vault where they are briefed by the disembodied voice of GLaDOS before being released through a portal. The player is introduced to the testing process and mechanics, eventually culminating in the procurement of the Handheld Portal Gun. As Chell makes her way through test chambers it becomes clear Motivating Chell with the promise of Cake at the end of the testing, Chell is put through tests of increasing complexity.

Portal: Still Alive
Portal: Still Alive is a Xbox 360 Live Arcade port of Portal, containing additional content in the form of new advanced chambers, inspired by Portal: The Flash version, with no additional story material.

Portal 2
Portal 2 was released simultaneously on PC & Mac, Xbox 360 and PS3.

Single Player
The narration in Portal 2 is completely differente, it introduces a clear separation in chapters (similar to the chapter in Half-Life), each chapter making the story progress. You still play Chell, equipped with the Portal gun, but the testing isn't a significative part of the story, not as much as in the original game, the story has more depth than simply testing.

Chapter 1: The Courtesy Call
Following the events of Portal 2: Lab Rat, Chell is awoken 50 days later in her relaxation chamber, which has the appearence of a motel room, for a 'mandatory physical and mental wellness exercise'. Returning to her long sleep, she is awoken an undetermined amount of time later by an unfamiliar voice at the door to find the room in a state of disrepair and the room intercom warning of an imminent core explosion. Upon opening the door she finds herself face to face with a Personality Core who introduces himself as Wheatley, the jovial AI in charge of the test subjects storage facility. After bringing Chell up to date, Wheatley moves her relaxation through the storage facility, crashing several times and almost destroying the room. After successfully navigating the room to the main facility, Wheatley instructs Chell to go retrieve the Handheld Portal Device, as it will be needed for their escape from the facility. Upon successfully acquiring the device, Wheatley and Chell make their way to GLaDOS's chamber where Wheatley claims a lift to the surface is located. They find the chamber partially destroyed and overgrown wildlife everywhere, and in the middle of the chamber lies the lifeless body of GLaDOS. Navigating to the breaker room under the chamber Wheatley attempts to find the breaker for the lift, in the process inadvertently rebooting GLaDOS. Bitter at the cause of her death, she crushes Wheatley and tosses him away before dropping Chell into the Emergency Intelligence Incinerator, into the incinerator room. GLaDOS instructs Chell to retrieve the two portal Handheld Portal Device, before guiding her back into the facility's test chambers. Fixing the broken down facility as Chell is forced through testing, the bitter GLaDOS informs Chell that her forced her to relive her own murder for decades.