When asked about the once-rumored Gears of War tile, Gears of War: Exile, Epic Games design director Cliff Bleszinski went on record to confirm to GameSpot that while the title was once in development, it was later canned. No further details were revealed.
"Let's just bury the hatchet now," Bleszinski said in the interview. "Gears of War: Exile was an unannounced game that I can't give any details about that has since been cancelled." It doesn't get much more concrete than that.
This is a story that extends all the way back to January 2011, when Epic trademarked the title Gears of War: Exile. A logo for the game surfaced at the time, and many speculated that a canceled Epic press conference from December 2010 would have been the official reveal for Exile.
A rumor in the late-2010 months suggested that Epic was working on integrating Kinect features into Gears of War 3. Bleszinski later put that rumor to rest, but he suggested that Kinect functionality COULD come to the Gears-verse. Many speculated that Exile was to be an on-rails Gears shooter for Kinect, but that belief was never proven.
It's all moot now, what with Exile being officially confirmed as a canceled project.