Abbreviated as 'MPO' the game will see Big Boss hunting down rogue members of his former unit FOX in South America. He will be able to recruit allies and fight alongside them in battle or control them directly.
Favourite characters including Ocelot, Eva, Major Zero, Para-Medic and Sigint are set to return and the story leads up to the creation of FOXHOUND, the Special Forces unit introduced in the original Metal Gear, at which time Solid Snake is a member of.
MPO will also feature online multiplayer built on the groundwork laid by Metal Gear Online in MGS3: Subsistence on PlayStation 2. The title will also retain the user-controllable 3D camera system introduced in Subsistence.