BioShock Infinite is a first-person shooter video game developed by Irrational Games and published by 2K. The third installment of the BioShock series, Infinite was released worldwide for the PlayStation 3, Windows, Xbox 360, and OS X platforms in 2013. The game is set in the year 1912 and follows its protagonist, Booker DeWitt, who is sent to the airborne city Columbia to retrieve Elizabeth, a young woman held captive there. Booker and Elizabeth become involved in a class war between the nativist Founders that rule Columbia and the rebel Vox Populi, representing the city's underclass. Elizabeth possesses the ability to manipulate "Tears" in the space-time continuum, and Booker and Elizabeth discover she is central to Columbia's dark secrets. The player controls Booker DeWitt throughout the game, fighting enemies and scavenging supplies, while the computer-controlled Elizabeth provides assistance. BioShock Infinite is a first-person shooter with role-playing elements. Infinite adapts the gameplay formula of BioShock, with weapons, powers, and upgrades often functioning similar as those in the earlier game, albeit named differently. The player may carry only two weapons at a time, and can collect other weapons and ammunition from defeated enemies or the environment. 8 In addition to guns and melee attacks, the player can use superpower-bestowing Vigors; these include the ability to shoot lightning, disable enemies by launching them into the air, or controlling enemies or machines. Vigors can also be laid on the ground as traps. 9–10 Vigors require Salt, the equivalent of magic points, to power the abilities.