BioShock Infinite is a first-person shooter video game in the BioShock series, developed by Irrational Games and published by 2K Games. 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.After the 2007 release of BioShock, Irrational Games and creative director Ken Levine initially wanted to do something different than a sequel. However, they later renegotiated with 2K to work on another BioShock game. Irrational based the game's setting on historical events at the turn of the 20th century, such as the 1893 World's Columbian Exposition, and based the story on the concept of American exceptionalism while also incorporating influences from more recent events at the time such as the 2011 Occupy movement. The relationship between Booker and Elizabeth became central to the story, with the team working to make Elizabeth feel like a real character rather than a computer-controlled sidekick.