Tom Clancy's Splinter Cell: Chaos Theory

Summary pulled directly from Steam - Some text may only be applicable to Steam platform

The year is 2008.
Citywide blackouts ... stock exchange sabotage ... electronic hijacking of national defense systems ... this is information warfare.
To prevent these attacks, operatives must infiltrate deep into hostile territory and aggressively collect critical intelligence, closer than ever to enemy soldiers.
You are Sam Fisher, the NSA's most elite black-ops agent. To achieve your mission you will kill from close range, attack with your combat knife, shoot with the prototype Land Warrior rifle, and use radical suppression techniques such as the inverted neck break. Also take on cooperative multiplayer infiltration missions, where teamwork is the ultimate weapon.
As the enemy evolves, so must you.

Deadly agility - Incredibly complete and fluid variety of moves including athletic moves, stealth moves, stealth kills.
Real weapons of tomorrow - The most complete arsenal of weapons and gadgets, from the knife to the experimental Land Warrior System.
As good as real - Never-before-seen graphics technology offers the best visuals on any system yet. Advanced physics engine allowing rag doll physics, particle effects, and perfect interaction with the environment.
Ultimate challenge - Intelligent AI with personal attributes, natural behavior where NPCs are aware of thier environments and remember past events.
Amazing replayability - Totally open level design with multipaths and optional secondary objectives.
Co-op stealth - Play multiplayer with friends and coordinate your infiltration in an all-new multiplayer challenge.

Please note that as of August 2016, the online features for this game are no longer supported. The Multiplayer mode / Co-op mode will no longer be accessible.