Players who take the role of Naked Snake in Metal Gear Solid: Portable Ops can sneak through a variety of missions in the single-player story or engage in stealth combat with friends by connecting to Ad-hoc and Infrastructure networks. Designed as the missing link in the timeline between Metal Gear Solid 3: Snake Eater and Metal Gear, the game begins in 1970, six years after Snake Eater when Naked Snake awakens in a South American prison camp.
Realizing the FOX unit ran off with a few nuclear warheads in the hopes of turning the Soviet Union into a melted snow cone, Snake follows their trail, treading carefully and silently through each objective in order to catch the culprits and prevent the demise of a nation. Silently stalking the enemy, Snake may also recruit up to three non-player medics, spies, snipers, and engineers or locate another player through a wireless search and invite them to play along. These chosen allies can be positioned where needed and players can cycle through each persona with the push of a button. Special characters can be downloaded at various "hotspots" throughout the United States and then traded with friends, creating a bartering economy within the wireless community.
Multiplayer action includes various additions to the Metal Gear competitive gameplay such as the "White Flag" system of defeat. Instead of battling to the death teams can opt to surrender and begin another game, and now leading players in "Deathmatch" are easier to spot as they have a croaking frog floating above their heads until the game is over or someone else gets a higher score. Players may also upload their single-player squadrons and use them in combat or swap them with friends.