Gears of War: Dark Horse is a Gears of War storyline co-authored by Anonymous ONI agent and Lieutenant Davis, with some contributions from other writers as well. It is the writers' own perception and expansion of the Gears of War lore, but in some cases it can be considered a separate continuity from the canon storyline.
Gears of War: Dark Horse is divided into three "segments": War of Nightmares, Unaware Survivors, and Rebuilt Dreams.