Hideo Kojima, the producer of the Metal Gear Solid series, has revealed during his podcast more details about the freedom players will have in Metal Gear Solid V: The Phantom Pain. Although it's something that's not really that surprising, Kojima stated that players won't be allowed to free-roam and explore the world during a mission.
Players will have all the freedom to explore the world when outside missions, allowing them to do sidequests and other activities, but things change once you accept a mission. After you accept a certain mission you are restricted to explore a certain area, and if you try to go beyond this area you automatically fail the mission.
Metal Gear Solid V: The Phantom Pain launches in early 2015 for PS4, PS3, Xbox One, Xbox 360 and PC.