Metal Gear Solid The Phantom Pain has a huge open world which you can explore at your own will, except in missions.
In Hideo Kojima’s most recent podcast he revealed that the player can explore the entire map with ease but once they accept a mission they must stay within a set are and if they leave that area they will forfeit the mission. The player will also fail the mission if they don’t complete the objective in a certain amount if time.
Metal Gear Solid V is released on PS4, Xbox One, PS3, Xbox 360, and PC early 2015.