Epic’s agreement with Microsoft as publisher socketed the studio into the Xbox 360’s flagship release calendar along with Microsoft’s biggest gun: the Halo franchise. Microsoft anticipated both Gears of War and Halo to release on two year cadences, so that the franchises could alternate.
As the console generation started, this seemed to work out, as Gears of War shipped in 2006, Halo 3 in 2007, and Gears of War 2 shipped on time in 2008. Epic expected that Bungie would follow suit with a new Halo game in 2009, leaving the holiday period in 2010 for a new Gears game.
This timing was important. While Microsoft was committed to advertising heavily for Gears of War, the competition for holiday advertising space and retail dollars would always be fierce, and it made little sense pitting Epic and Bungie against each other.