Portal is a single-player first-person action/puzzle video game first released as part of The Orange Box collection of games released in October 2007 for the Xbox 360, PS3, and PC. The game was included along with more established titles Half Life 2, and Team Fortress 2, but, somewhat unexpectedly, Portal became a standout on its own, with many gamer's buying the box set for Portal alone. It was released as a standalone game for the PC on in October 2007 for $19.99, and retail games appearing in stores on April 9th, 2008. Portal was released on Xbox Live! arcade on October 22, 2008 for 1200 points.
In Portal, the player controls the character, Chell, from a first person perspective as she is challenged to navigate through a series of rooms using the Aperture Science Handheld Portal Device ("portal gun"). The portal gun can create two distinct portal ends, orange and blue. Neither is specifically an entrance or exit; all objects that travel through the one portal will exit through the other with no change in momentum magnitude. If subsequent portal ends are created, the previously created portal of the same color is closed. Not all surfaces are able to accommodate a portal, and any attempt to do so will not affect the existing portals. Chell can also pick up objects, though she can only throw objects a short distance (affected by the player's momentum). These objects ("Aperture Science Weighted Storage Cubes" or a "Weighted Companion Cube") can be used to press large buttons to open doors or activate platforms, but barriers (known as "Material Emancipation Grids" or 'fizzlers', as described by the audio commentary) at the end of each test chamber or within certain test chambers prevent the player character from carrying such objects beyond them. Passage through these fields also closes any open portals, and portals cannot be fired through these fields
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