Portal is a first-person puzzle platform game in which the player sees from the main character’s point of view as she moves through space and time. Gameplay consists of a series of trials that can only be accomplished by moving the central character—a woman named Chell—through flat planes using a device that creates portals (holes) in walls and floors. Chell is instructed to work her way through a seemingly endless string of enclosed spaces by a disembodied mechanical voice called GLaDOS (Genetic Lifeform and Disk Operating System). The promised reward for finishing these challenges is cake. In the game’s virtual environment, the character can move in unexpected ways, her spatial freedom reminiscent of the optical vertigo of a drawing by M. C. Escher. Unusual for the genre, the violence in this first-person shooter game is aimed at walls.
from Applied Design, March 2, 2013–January 31, 2014