Metal Gear Solid V: Ground Zeroes is just the tip of the iceberg that is Metal Gear Solid V: The Phantom Pain.
During an interview with Siliconera, series producer Hideo Kojima talked about just how gargantuan The Phantom Pain would be when compared to Ground Zeroes.
GZ is both a prologue to the MGSV story and, at the same time, a tutorial for a new MGS, which transitions to sneaking simulator. With that said, GZ has a relatively small field as compared to the main game (which is hundreds of times larger) without time zones changing in real-time. However, each mission offers different time zones with different playstyles.
It makes sense that Ground Zeroes would serve as a means to get players ready for the full Phantom Pain experience. While past MGS games have had big levels (MGS3 and 4 specifically), the series has never had a gigantic open world. Die-hard fans of the franchise can play on the small open world of Ground Zeroes and not feel to overwhelmed. This will also serve to prep them for the vastness of The Phantom Pain.
The Japanese concept of open world isn’t like the Western one so I had thought that perhaps MGSV would just have bigger areas to play in. It seems as if I was wrong and The Phantom Pain will be a full on open world extravaganza.
While Ground Zeroes will be released on March 18th of this year, we’ll have to wait significantly longer for The Phantom Pain. It may be a long time before we get to experience this monstrous open world that Kojima is promising.