Hideo Kojima clarifies what he meant by "open world" in Metal Gear Solid 5.
Stealth games usually stick to interiors. You go from one point to the next to complete your mission. Back when Hideo Kojima first started showing gameplay for Metal Gear Solid 5, he revealed he wanted to create a "true open world experience." In a Famitsu interview, Kojima explains what he imagines his open world game to be.
"Of course it's not going to be a game where Snake fishes all day or changes jobs and pursues a different life," Kojima said. "The game map is an open world and you have freedom in that way, but in MGS, it's clear what you're doing. That may be 'I have to help someone' or 'Destroy this thing' or 'Go gather intelligence at this spot.' Some missions will have time limits, too."
Previous games in the series have had aspects of both linear and open world games. As a player, you can choose to sneak past foes or to kill them. At the same time, the games have taken place in interiors where the player is placed at an entrance and follows a path to the next event. "It's not that linear games are bad... but really, it'd be fun if you were the one thinking about how and where to infiltrate, what sort of equipment to bring, and how to get out of there... I think the way that MGS is combined with an open world here is something that we haven't really communicated very well yet." He believes many future games will lie within open worlds because of their interactivity.
Kojima has previously worried that the open world experience of Grand Theft Auto V would outperform his own series. Of course, the two series have very different themes and try to accomplish different things. He believes that despite the change in gameplay, people will still pick up Metal Gear Solid 5 and say, "Yes, this is MGS."