After the 2007 release of BioShock, Irrational Games and creative director Ken Levine were initially uninterested in creating a sequel, but they later renegotiated with 2K to produce 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.The game's development took five years and involved hundreds of employees at Irrational, in addition to support studios. The development process was troubled, with Levine's management style resulting in wasted work and missed deadlines. Outside help was brought in to make sure the game shipped. BioShock Infinite was supported post-launch with downloadable content, including the story expansion Burial at Sea, which links Infinite's story to that of the original BioShock game.BioShock Infinite received critical acclaim, with praise particularly directed at its story, setting, visual design, and art direction. It has sold more than 11 million copies worldwide. Infinite was released on PlayStation 4, Xbox One, and Nintendo Switch as part of BioShock: The Collection.