Way back in the long, long ago of January 2011, a trademark on the US Patent and Trademark office website surfaced for Gears of War: Exile. Epic Games design director Cliff Bleszinski has revealed that the studio was working on it, but it has since been canned.
"Let's just bury the hatchet now," he told Gamespot here at PAX East. "Gears of War: Exile was an unannounced game that I can't give any details about that has since been cancelled." Outside of the existence of the trademark, there really isn't any other information.
Some have speculated Gears of War: Exile was to be a Kinect title, an on-rails experience, but without any further information from Epic, it looks like we're left to speculate on what could've been.