The developer soon began work on its two titles: "Killzone" (in development for Sony Computer Entertainment for the PlayStation 2) and "" (in development for Eidos Interactive for the PlayStation 2, Xbox and Microsoft Windows). Both titles would be released the following year to mixed reception, however "Killzone" enjoyed pre-release hype and anticipation, and despite some backfire effect due to the media hype, "Killzone" went on to sell over a million copies worldwide, earning Greatest Hits and Platinum status in North America and Europe respectively. Guerrilla signed an exclusive development agreement with Sony Computer Entertainment in March 2004, that would see future development solely for Sony's line of video game consoles, the PlayStation 2, PlayStation Portable and PlayStation 3.