Metal Gear Solid V: Ground Zeroes has been described as many things. A prologue to Metal Gear Solid V: The Phantom Pain, a “pilot” episode, and even a tutorial. Series director Hideo Kojima reiterates in an interview with Famitsu that a tutorial to The Phantom Pain is precisely what Ground Zeroes is meant to serve as.
That said, Ground Zeroes is missing a few features that will be present in The Phantom Pain, Kojima reveals. For starters, the game will not feature dynamic weather. Additionally, while the Side Ops missions take place during the day time, the rest of the game will take place at night time, in the rain.
Kojima also mentions that your save data from Ground Zeroes will carry over into The Phantom Pain, and it appears that the things you do in this game will have some affect in The Phantom Pain. As an example, he mentions a stage in Ground Zeroes where you have the option of saving soldiers versus not saving them. If you do save them, you will be rewarded in The Phantom Pain in some fashion.
Additionally, Kojima confirms that the base-development features that were introduced in Metal Gear Solid: Peace Walker will be making a return in The Phantom Pain. Since The Phantom Pain is a more realistic game than Peace Walker, bringing soldiers back with you will cause your base to grow.
Echoing comments that he’s made in the past, Kojima also shares that the reason Metal Gear Solid V: Ground Zeroes is being developed and released sooner is because The Phantom Pain has a lengthy development cycle due to the amount of content. Having part of the experience available as a “pilot” episode of sorts allows players to try the game out prior to release.
Finally, whenever The Phantom Pain is released, Kojima says he’d like to include something to reward players that own both games. Just what this will be hasn’t been decided upon yet, however.