Ssshhh. You hear that? A rustle of cellophane. The sinister snapping of Amaray plastic. Then bam! We're out cold. That's what would happen, we imagine, if games somehow developed artificial intelligence, appendages and, erm, the ability to jump off the shelf and assault us. Well, Chaos Theory would, at least. But put down the crack pipe, it's more than just belief in the surreal you'll need to suspend whilst playing Tom Clancy's latest stealth-'em-up. Without doubt, this is one of the best-looking games we've ever seen on Xbox. Chaos Theory is the true successor to the groundbreaking Tom Clancy's Splinter Cell, developed by the same studio that created the original. Pandora Tomorrow was a brilliant stop-gap, but a swift sticky shocker and sleeper hold later, and CT jumps in to relieve command and establish itself as the true sultan of stealth.

If there's one assumption CT does make, it's that the vast majority of its audience will have played, at some stage previously, one of its little brothers. The obligatory pretty cutscene opener details the latest international crisis tempting Sam Fisher out of retirement. Your cast of supporting team members, including no-nonsense tutor Lambert, simply informs Sam in the excellent standard of voice acting we've come to expect, which exotic location and sinister enigma he's being shipped off to visit next. Comprehensive Training videos immediately reiterate the Fishter's espionage ability for the rusty, and detail his incredible new array of skills and kills for everyone else.

Refreshingly, this cut-the-crap approach does allow players to tweak and tailor their equipment before each mission. Go underground like The Jam with sticky cameras and shockers in the Stealth option. And when the situation looks like it could all go Die Hard on you, pack extra ammunition and grenades with the trigger-happy Assault option. Catering for both ends of the patience spectrum, this is a great touch that adds healthy substance to the mix. Indeed, Splinter Cell Chaos Theory tries to pack in more diversity than a shelf full of Kellogg's variety packs, boasting multiple paths through levels. Granted, you'll ultimately reach the same funnel points, but CT's levels feature a myriad of routes through, each posing different puzzles and setpieces to conquer. It makes the original look more railed than London Underground.

Like a Chateauneuf, Sam Fisher has definitely got finer with age. We're not making any slanderous accusations of Botox or Just For Men to hide the ravages of time, but the visuals in CT are truly enlightening. Gorgeously lit levels create some amazingly atmospheric - and realistic - shadows to lurk in. The cod liver oil's been doing the trick too, as Sam's slinky, cat-like movements are animated in a stunningly believable way.

For a party with a happy atmosphere, CT delivers like a sticky shocker to the nether regions. Aside from utterly astounding visuals and lighting, the brilliant score perfectly accentuates the immersive atmosphere; subtle and almost unnoticeable during more clandestine moments, rousing to heart-pounding intensity during firefights. Turn up the 5.1 and you'll be jumping out of your pants (what better lone attire is there to play games in?) as bullets crack and ping around you, shattering glass and plaster with frightening realism.

To complement his visual makeover, Sam packs some killer moves too. If Pandora Tomorrow provided the whistles (Black button), Chaos Theory sees Sam boast killing ability with bells on. Entice a guard to your secluded spot and tap the R trigger to execute a no-nonsense, silent kill even Tom Berenger's Sniper (One Shot, One Kill, One Crap Film) would be proud of. There's no gratuitous gore, just a slick, satisfying feeling of getting the job done. It doesn't pay to be quite so knife-happy all the time however, as CT continues to press home the fact that stealth gives wealth. Of information, that is. Grab a guard, interrogate him, and often he'll cough up (before the blood) some very handy info pertaining to the mission, be it door codes or hints on how to navigate tripwires and traps. You'll occasionally get the same information by eavesdropping on a conversation (instead of blithely barging in, frag grenade in hand), yet this doesn't compare to the titillation of hostage taking.

Enemy AI yet again pushes the boundaries beyond what we've previously experienced. Guards often patrol in groups, and lone gunmen aren't afraid to immediately call in their mates if they spot anything untoward. Instead of merely investigating the problem and then promptly disappearing (Stolen, put this dunce's hat on and go sit in the corner), they'll remain in the area till you either discreetly dispatch their number, or evade the now doubly complex patrol patterns. The point of 'Stealth First' is hammered home even more succinctly here. In the previous games, guards would elevate their alert status by progressively donning body armour and helmets. Here, the paranoid perps will suit up quicker than a chauffeur caught with his boss's wife, ultimately fortifying their defensive positions once the alarm stages reach level four. Face shots only here folks, and frickin' hard ones at that. However, this is finely balanced with the welcome addition of a Noise meter, where the varying level of detectable noise you're permitted to make is displayed.

Failing that, your cool thermal vision soon points an accusing finger at heat-emitting Mercs and the like, giving Sam the ability to snipe from a safe distance through their thinly veiled cover. Solid cover isn't a lot safer either, as superb physics see bullets penetrating, pinging off objects and cannoning into enemies. Once again, great AI sees them take up intelligent firing positions, though short, controlled bursts will keep their heads down long enough for you to figure out just what the hell you should do.

In a pleasing bid to make the game more accessible, players can carry on even after they've triggered alarm after alarm, as long as the primary objectives are met. Another huge improvement is the new instant save feature, sure to see a significant drop in heart conditions; no more scraping to the next checkpoint, ammo dry, and with only spit balls and foul language to get by.

The new streamlined interface is less clunky than previous games, and makes selecting weapons and attachments for your SK-20 easier than ever. Gone is the so-last-year PDA system, replaced by a one-touch button menu, but this now means you have access to a brilliantly useful, fully interactive 3D map. Your objectives are clearly displayed, so there's no confusing (read: bloody irritating) backtracking through levels if you've lost your way. Emails are the new data sticks, and when coupled with the odd loud-mouthed guard, provide a perfectly paced drip feed of information with which to complete the mission.

Dispelling the myth that all gruff-voiced, reluctant action heroes like to work alone, CT now offers the superb option of two-player co-op. If Pandora Tomorrow opened the closet doors for dressing in black rubber and lurking in the shadows with fellow espionage enthusiasts, then CT will quite literally blow them off. It's the addition of this fantastic Co-op mode, coupled with seriously innovative features that genuinely enhances the gameplay experience, that makes CT more than just another sequel.

Sod frantic shooters, the subtle craftiness of Chaos Theory has reignited our passion for the precise, methodical approach, something that's been frustratingly absent from a title since, well, Pandora Tomorrow. Awesomely exciting and heart-stoppingly tense in turn, Fisher and co prove the law of diminishing returns completely wrong, and deliver the most complete and cool stealth 'em up we've ever seen. You're never too old for hide and seek when it's as good as this.

1. Jaw-dropping visuals, beautifully created shadow and lighting, and an all-round stunning atmosphere show the true capabilities of Xbox.
2. Amazingly absorbing. You'll soon be donning a balaclava and swimming goggles and hacking into your dad's "photo collection".
3. The new instant save feature takes away the frustration of backtracking without cheapening the (still tough) setpieces.
4. Two-player Co-op, through either split-screen, System Link or Live is incredible fun. Suit up for another dimension in multiplayer gaming.
5. Amazing enemy AI, a bigger batch of gadgets and Fisher's impressive new moves continue to evolve the series.

Elegant, engaging and electrifying, Fisher mercilessly silences any competition. The best Splinter Cell yet.