"Once you've got an enemy in your sights, you've got a bunch of new options for taking him out. If he's facing you and you can't get him in a chokehold, pressing the left trigger will knock him out with a knee to the chest and a knock on the head. If he's turned away from you, though, you can either take him down with a swift punch, or you can grab him (as always, using the A button) before knocking him over the head. There are also a few kills that are location dependent, including one in which Sam, hanging from an overhead pipe, reaches down to snap his foe's neck. The biggest change in close quarters combat, however, is Sam's ability to use his knife.

Using the right trigger, you can quickly unsheath your knife and stab your foe in the chest before he can even make a sound. It's fast, it's brutal, and it works like a charm. If you're attacking from behind, you can cover his mouth before stabbing him in the back, or you can grab him and drag him into the shadows, finishing him off with a clean cut across the throat.

The SC-20K is back, complete with the usual assortment of spy gadgets like sticky cameras (you can shoot two now, switching between them when needed) and sticky shockers (try firing one into the puddle at your opponents' feet). If you need a better view of the situation at hand, clicking the left analog stick will switch back and forth between each shoulder, allowing you to choose the perspective you'd like. Sometimes a little more firepower is needed and, in a first for the series, Sam can switch (by pressing the Y button) the SC-20K to shotgun mode for maximum damage.

When an opponent gets a shotgun blast in the chest, his body flies back realistically, showing off the game's new ragdoll physics system. It's particularly noticeable when carrying bodies around, as you can now finally drop them off of edges of buildings and out of windows. The enemies, however, try their best not to become corpses, thanks to a reworked AI system. Foes will sprint away from thrown grenades, and they'll hide in waiting for you to come toward them after the smoke clears.

The levels in Chaos Theory seem to be much less linear than the previous games, offering players the chance to take a variety of routes in order to complete the stage. In certain areas, you can even create new pathways with your trusty knife, slicing through plastic sheeting or canvas to reveal a hidden hallway. You can even sneak through crawl spaces, skipping sections of the level altogether.

With the promise of some innovative cooperative multiplayer and the return of the amazing online head-to-head mode, Chaos Theory is looking like another fantastic game in what's starting to become the best stealth series around" (xbox.gamespy.com).