The Ground Zeroes will be the stand-along prologues to Phantom Pain as explained by series creator Hideo Kojima.
"Maybe you could think of a standard Hollywood movie where you have 15-20 minutes then the title, and then the main story starts," Kojima told Kotaku. "So all of the events leading to [Phantom Pain] will be happening through the game. You can think of Ground Zeroes as this."
The prologues will be out in the spring of 2014 for $30 on Xbox One, 360 and PlayStation 3 and 4. However Phantom Pain has no release date yet.
Check out 12 minutes of the “plant” mission for Ground Zeroes which ties-in directly to the story of Phantom Pain as Kojima explains:
"Within that big mission of Ground Zeroes you have several side elements, collecting specific items, doing something within a certain amount of time... In the side-ops you will find several elements scattered, and when you put them together, it will put together a story within the player's mind of what is the next part of the game."
Another exciting detail is that the Ground Zeroes will include a classic Solid Snake player skin on PlayStation and also include exclusive missions for the console.