Metal Gear Solid 5: Ground Zeroes campaign will be incredibly short according to an article in Game Informer. By on February 4, 2014 at 2:26PM PST ...

Ground Zeroes serves as a prologue to the other Metal Gear Solid 5, The Phantom Pain, with the Steam description proclaiming that it "gives core fans the opportunity to get a taste of the world ...

Kojima said that Ground Zeroes was originally conceived as a prologue to MGS 5, introducing players to Snake’s vengeance. The overall theme would be that of retribution.