In Sam Fisher's first next-generation adventure, the splinter cell has a tragedy befall him. Shortly thereafter, Sam's life collapses around him. He becomes more distant from Third Echelon. In fact, he even goes so far as to get himself arrested.

But it's all part of the plan. Sam Fisher is now a double agent, working for both the NSA and a terrorist organization known as the JBA, or John Brown's Army. Sam is for the most part a good guy still. But will that remain? Will Sam do good for the NSA and bring the organization to justice, or will the lure of the terrorist group overpower and overcome Sam?

The choices you make affect that outcome. Moral questions will pop up in various places throughout the game. Do you shoot a prisoner to earn trust with the JBA, or do you hold off, keeping the NSA on your side? Whatever outcome you decide on, your trust with one will go down and the other will go up. This trust system is a new addition to Double Agent.

As you work your way through ten missions, your best friends are shadow and silence. You can go in guns blazing, but you won't get far. As a master spy, Sam will have to sneak around crates and walls, hide under vehicles and tables, sneak through highly guarded areas, and bypass electronic, fingerprint, voiceprint and retinal locked doors. You must interrogate or hack for keycodes and combinations, and you have the choice of knocking an enemy unconscious or killing them. When hanging by a rail, you can let an enemy guard walk by, or reach up, grab him and throw him to his death. Your best weapon is your mouth. Lure an enemy to your location by whistling, then sneak around him as he abandons his patrol to find the source of the noise. Your configurable weapon is really a backup.

Sam will go on many missions as a double agent. You'll be visiting the JBA headquarters in New York City, you'll travel to the Congo to rescue a soldier, you'll board a cruise ship in Cozumel wearing shorts in broad daylight with minimal cover, forcing you to change your stealth patterns. You'll wind up in the middle of a wartorn city, in the middle of a battle between guerrillas and the military, both of which want you dead. Your missions are varied, and all can be completed without firing a single bullet.

Multiplayer is similar to the past Splinter Cell games. You take on the role of either a spy or a mercenary; spies are played from the standard, third-person perspective, while mercs are played from the first-person perspective. Spies are tasked with stealing sensitive documents; mercs are tasked with killing the spies and protecting the documents. Each side has its own unique weapons and items. Spies do not have conventional weaponry, meaning nothing that can kill a merc, but they have several gadgets and devices to help them. Mercs are blessed with a high-powered rifle, grenades, and the ability to toggle various vision modes.

The PS3 version includes some additional content: a new female spy character (multiplayer), two new maps based on a new environment (multiplayer), a new set of co-op challenges and some refinements for the existing content.