Sony PSP

Metal Gear Solid: Portable Ops Plus is a multiplayer-focused expansion of Portable Ops. It is a standalone disc, though owners of the first title are free to transfer characters. The "Plus" aspect translates into new soldiers, updated play modes, additional maps, and an experience-based progression system. The original game's Story Mode has been dropped in favor of an Infinity Mode, which offers 50 stages of sneak-and-shoot action. While the primary goal is to find your way toward a randomly generated exit without alerting guards, a secondary objective is to neutralize enemies so they can be added to your multiplayer squad.