 The developers of Portal 2 initially envisioned it as a prequel to Portal set in the 1950s, long before GLaDOS took over the Aperture Science facility, with events set in motion when Aperture CEO Cave Johnson becomes trapped within a computer. Johnson would have led an army of robots, which would battle against the player to rise to power within Aperture. In June 2008, based on information from a casting call website and leaked script samples, Kotaku reported that Valve was seeking voice actors to play Johnson, named him as an AI and identified the game as a prequel. Valve attributed this leak to an "overeager agent". Following negative playtester feedback about the omission of Chell and GLaDOS, Portal 2 was re-conceived as a sequel. The team returned to the idea of exploring parts of the facility from Aperture's early days, and reincorporated Johnson through a series of recordings.
