Sam Fisher has become one of the most well-known names in video games, and due to his debut game appearing first on the Xbox he has a special place in the hearts of Xbox owners. Splinter Cell Double Agent is Sam's latest adventure, and also marks his next-gen debut, again on an Xbox. While Double Agent isn't quite a truly next-gen experience, feeling rather similar to Chaos Theory, fans will appreciate more great stealth action.

Having said that Double Agent plays in largely the same way as Chaos Theory, it would only be right to contradict myself right from the off. You see, there is one major new element to Double Agent that makes you consider each and every action you take in the game. As the game's title suggests, Sam goes undercover, and to remain undercover he needs to be trusted by his employer (the NSA) and by a terrorist group known as the JBA. Each objective in the game has an impact on how each side trusts you, and this forces you to think in a completely new way.

Failure to perform a certain task could end your mission there and then, but your actions have a more far-reaching affect. Say you finish a mission with the NSA on your back, after failing to plant a virus on a computer system or something equally spy-like; this not only hurts your rating for that mission, but carries over to the next. Starting off a level with a low trust level from either party will basically mean that you have to play the mission by the book, with slip ups being very costly indeed. It really is a rather unique gameplay mechanic, and sets Fisher's latest outing apart from the rest.

As ever, gameplay is focussed on stealth and not action. The key to success in Double Agent is to remain unseen and to take people out as quietly as possible. Not only will this keep you alive, but it'll help you complete a number of extra objectives during each mission. The best way to deal with enemies is to sneak up on them, grab them, and then smother them or crack them over the head, but if you need to you can fall back on guns or a rather brutal up close and personal knife to the gut. Killing rather than knocking out enemies will more often than not hurt your trust ratings, but the option is there if you think it's worth the risk or if you're told to kill.

Gadgets once again play a part, and successfully completing certain objectives will unlock new items for use in the game; you'll get hold of the usual bunch, such as sticky cameras and enhanced vision modes. One of the most useful gadgets is worn on Sam's back, and indicates how visible you are to enemies. Green is obviously safe, yellow is getting a little close for comfort, and red means someone's going to be firing at you very soon. The enemies are all excellent shots, so unless you get to cover very quickly, a red light almost always means mission over. Sam also comes equipped with a handy watch (complete with 3D map), and an overhead map of the area, which marks enemy locations when you stand still.

The ice break is one of Fisher's new moves

Numerous levels take place at the JBA HQ, and these sections of the game throw numerous sneaky objectives at you, which need completing within a strict time limit. Once again you'll be required to remain trusted by both parties, and in a building full of terrorists, this isn't easy. Simply wandering into a secure area will set alarm bells ringing in the mind of anyone who happens to spot you, and trying to keep out of sight while in a hurry is something that takes more than a little trial and error. These levels certainly have a different feel to the usual Splinter Cell gameplay, and throw up some very interesting challenges and moral decisions.

If there's a weakness to the single-player campaign it's the story. Sam goes to prison and his daughter is killed in a car accident, but this is all covered in a tiny intro after the first level, and there's no real emotional involvement at all. Given that the whole premise of the game is about making hard decisions, the weak storytelling is a real letdown and makes you feel rather disconnected from Sam and the actions he takes. The JBA HQ missions do give you a neat insight into what's happening inside the terrorist organisation, but there's still room for a lot if improvement.

If Sam's stealth meter is red, you're in trouble.

Following one of the greatest looking Xbox games was always going to be hard, but Double Agent is certainly an impressive looking game. Character models are hugely detailed, environments are large and take you to a number of different locations, the lighting in certain missions is stunning, and the frame rate holds steady for the most part. You will notice some slowdown during particularly effects-heavy sections, and animations don't quite gel together as well as they really should, but on the whole Double Agent is a fine next-gen debut for the series.

The Splinter Cell series has always excelled in the audio department, and Double agent continues that tradition. Sam is once again voiced superbly by Michael Ironside, and President Palmer himself Dennis Haysbert reprises his role as Lambert. Both do a fine job, and are joined by a fine accompanying cast, although the humour heard in exchanges in Chaos Theory is notably absent here. A suitably espionage-themed soundtrack fits perfectly with the in-game action, and other than a number of recycled sound effects from Chaos Theory, there's very little to complain about.

Multiplayer has played a part in the last two Splinter Cell games, and the Spies Vs. Mercenaries gameplay returns, but it's been changed a fair bit. The biggest difference comes from how each class controls. The spies have become almost monkey-like, able to throw themselves around, clinging to ledges and pipes as if they've got a tail they can use as an extra limb. At first their acrobatic moves are hard to get the hang of, as they move so differently to Sam Fisher. Mercs are once again restricted to a first-person perspective, and although up against a far more nimble enemy, are more than powerful enough to put up a fight.

Double Agent's online offering bumps the player count from four to six, allowing matches of up to 3 Vs 3. Rather than complicate things by having different objectives for each map, all of Double Agent's ten maps (of which some require you to gain experience before they are unlocked) pose a fairly straightforward task. The spies need to download data from various terminals and return the data to their insertion point, while mercs need to prevent them from doing this. Tactics are still quite complex, with the differences in abilities between the two classes being massive, but the online play is far easier to get into than in previous Splinter Cell games.

JBA HQ missions provide some different challenges

One of best features in Chaos Theory was the rather brilliant co-op play, which saw you and a mate tackle proper missions together. This mission-based co-op has sadly been dropped in Double Agent, but you can play with up to two other players as spies against AI controlled mercs. These co-op missions are similar to the multiplayer levels, and aren't nearly as good as those in Chaos Theory, but if you want to tackle bots with some mates, they're good for a few hours of entertainment.

Splinter Cell Double Agent isn't the next-gen Splinter Cell experience that Ubisoft might want us to believe it is, but it's still a very impressive single and multiplayer experience. The single-player campaign is excellent throughout (bar a rather out of place opening level) and the multiplayer has been changed to allow more people to enjoy it. The double agent element gives the game a slightly unique feeling, but at times it's hard to shake the thought that you're playing a Chaos Theory expansion pack; albeit a very attractive one.