 A standalone version, titled "", was released on the Xbox Live Arcade service in October 2008, which added 14 puzzles to the gameplay, and a sequel, "Portal 2", which was released in 2011, adding several new gameplay mechanics and a cooperative multiplayer mode.In "Portal", the player controls the protagonist, Chell, from a first-person perspective as she is challenged to navigate through a series of rooms using the Aperture Science Handheld Portal Device, or portal gun, under the watchful supervision of the artificial intelligence GLaDOS.The portal gun can create two distinct portal ends, orange and blue.