"Ground Zeroes is basically a prologue, and [it] takes place about nine years prior to Phantom Pain ... put together, these two pieces comprise Metal Gear Solid 5," said Kojima. "And The Phantom Pain is the main part of the game, and it's really a huge game." As for where Ground Zeroes fits into the Metal Gear Solid chronology, Kojima said it is set "almost immediately after [Metal Gear Solid: Peace Walker]."
While Kojima said he "can't comment just yet on how these things will be distributed and sold," he said Ground Zeroes will arrive before The Phantom Pain to give players a taste of the larger experience "on a smaller scale."
"[Ground Zeroes will] allow the user to jump in, learn how to sneak in real time in that world, that open world," Kojima explained. "And then later on, after they kind of get used to that, then Phantom Pain will come along, and they'll be thrown into this huge, gigantic open world."
Kojima also confirmed to GameTrailers that David Hayter, who has voiced Solid Snake and Naked Snake (aka Big Boss) in every console and handheld Metal Gear Solid title from 1998's Metal Gear Solid through 2010's Peace Walker, will not return for Metal Gear Solid 5. Kojima wouldn't say who the new voice actor is, but as for why Konami didn't ask Hayter back, he said, "What we're trying to accomplish here is recreate the Metal Gear series. It's a new type of Metal Gear game, and we wanted to have this reflected in the voice actor as well."
"we found a Swedish guy to stand in"
That design, according to Kojima, is one of a truly open stealth game. He contrasted it with the Metal Gear Solid titles to date, describing the previous games as "kind of like a story on rails." In Ground Zeroes and especially in The Phantom Pain, said Kojima, you'll choose when and where to infiltrate a compound, and the situation will vary based on those decisions. For example, undertaking a mission at night means you'll encounter fewer guards than in a daytime mission, but it'll be tougher for you to see.
Asked why he went through the rigmarole of debuting The Phantom Pain at the 2012 Spike Video Game Awards and acting as if it were a new game from a new studio, Kojima explained that his studio, Kojima Productions, "wanted to do something to really energize the community," even though he knew the fans would figure out the ruse. GameTrailers' Geoff Keighley interviewed someone purporting to be Joakim Mogren, the supposed CEO of The Phantom Pain developer Moby Dick Studio, a few weeks ago on GameTrailers TV. But Kojima explained, "We found a Swedish guy to kind of stand in and do that interview."
More importantly, said Kojima, Kojima Productions wanted to get unbiased impressions of its new Fox Engine.
"We wanted to put the game out without revealing that it was Metal Gear Solid, and just see how well it would do, just based on the visuals of the Fox Engine," Kojima explained. "In many ways, we're threatened by the games from the West; there's a lot of competition out there. So we really wanted to reinvent ourselves with this game, reinvent the series."
Check out GameTrailers' 18-minute interview with Kojima above for much more on Metal Gear Solid 5, including details on the debris and bone embedded in Snake's forehead, the abilities of his cyborg arm and the game's cast of old and new characters.