Tom Clancy's concept for Rainbow Six first appeared as the subject of his best selling novel in 1998. Now, ten years on, the concept has grown into a vast franchise encompassing books, a movie planned for next year and, in its best-known form, game release after game release. With so many titles carrying the Rainbow Six brand, there is always the risk of a series going stale. Thankfully, Clancy's creation isn't showing any signs of faltering, with Rainbow Six: Vegas 2 delivering a very impressive sequel to the excellent original.

As can be assumed from the title, Vegas 2 sees everybody's favourite elite counter-terrorism force back in Sin City - and it's certainly living up to its name, with a multitude of chemical explosives hidden about the place, crazed gunmen and ruthless mercenaries fixing you in their crosshairs and, of course, a story laced with themes of duty, honour and bitter betrayal.

You take control of main character Bishop (and, if playing co-op, the second player is his recruit Knight - the wordplay is almost painful). Straight away, you find yourself fully immersed in your character, thanks to the extensive (for a first person shooter) character creation where you can pick a face for Bishop (who can be male or female) or you can even map your own features to the character using the Xbox Vision camera. Although slightly buggy, this is a great touch and seeing your own face in game when taking cover and reloading creates an even stronger bond with the character. Just try not to be too overwhelmed at the sight of your own bullet-riddled corpse whenever your opponents triumph! You can also unlock various different types of camouflage to dress your character in. This is, somewhat disappointingly, a purely cosmetic change; it would have been nice to have a system such as that found in Metal Gear Solid 3 where your choice of outfit affects your visibility in any given environment.

The story itself doesn't offer anything new if you're familiar with this type of game. You'll encounter the standard fare of eliminating terrorist threats, hunting for bombs and rescuing hostages across a number of varied locations. The overall impression is that of a series of weakly linked environments, rather than a truly engrossing narrative. Another initial problem with the story is that, despite its name, it isn't immediately apparent that Vegas 2 is a direct sequel to the original game. The plot follows a separate team in events that take place prior to and then in parallel with those of Rainbow Six: Vegas. Whilst a bit of a letdown after the cliffhanger ending of the original, all loose ends are eventually tied up, even if some of the twists feel rather clumsily inserted. This is slightly disappointing after the fantastic plot of the original Vegas, but the story isn't really what you buy this game for and it works well enough to provide some reason for your actions as you move through each level.

Visually the game takes much from its predecessor, with no obvious improvements on the graphical front. Even after more than a year, however, the graphics still look relatively fresh and the levels are filled with detail and accurate, glitch-free character models. The only slight issue I had was that it is sometimes difficult to see the plain white objective marker with everything else that's happening onscreen, especially when it is behind you. I was initially disappointed by the lack of glitz in the environments - Vegas 2 does not make the most of the spectacle of Las Vegas as its predecessor did. The levels feature more run-of-the-mill locations, with one notable exception to this, during an infiltration mission that's set against the tongue-in-cheek backdrop of a Major League Gaming competition, in which, as of the 2008 season, Vegas 2 is a major fixture. This sees you diving behind slot machines and firing through posters and notice boards (providing a fantastic example of the revamped bullet penetration system, which now takes the composition of items of cover into account). While we're on the subject, product placement is noticeable in the game but the producers have also included a decent number of fake products, making the actual advertisements less noticeable so that the game's overall aesthetic is never spoiled. Be warned though - you will notice the odd salute to previous Ubisoft projects and collaborators - and I seriously doubt that everyone in the state of Nevada really drives one of five Dodge-built vehicles!

Where Ubisoft really shine is in their level design. Every building features at least two points of entry and there is never a single linear route through a level. Despite all these possibilities, you are still never overwhelmed and don't run the risk of getting lost in the wrong corridor or find yourself accidentally backtracking. Momentum is never lost from your progression to the next area and you always find yourself pushing forward.

Another treat is to be found in the extensive arsenal of handguns, SMGs and rifles encountered throughout the game. Each weapon is beautifully and realistically modelled and every gun has a satisfyingly different sound when fired. Flashbang grenades also produce a dizzyingly realistic effect, both in their cornea-melting burst of light and the deafening effect that is experienced by players and enemies alike when in close proximity to one going off. When you're not having your eardrums exploded by nearby grenades, you can enjoy the in-game music, which is used to subtly build tension and add drama to firefights. This is never overpowering while playing and you will find yourself humming and singing along with the game before you actually acknowledge the music - a great sign of a true mood-setting score. The voice acting is solid, but enemy cries and orders quickly become repetitive, with the same sound bytes used for most terrorists. This can be especially frustrating in the larger battles when you start to notice their phrases coming in cycles. It's less of an issue for you and your team however, with orders coming from you serving a functional purpose and the replies of your squad feeling reassuring rather than repetitive. Still, hearing your British teammate purring "with pleasure" whenever you order him to silence his weapon is always amusing, if a little unnerving.

So far, Vegas 2 may seem impressive but still only at the high end of average, but it is the effort that Ubisoft has put into the gameplay that raises the experience to exceptional. Whilst the difficulty level is constantly challenging and rewards patience over the usual run-and-gun first person shooter attitude, this is an incredibly easy game to play. At the core of the experience is the intuitive control system; all team commands are assigned to the A button and d-pad, allowing you to issue quick and clear orders - a godsend in frantic assaults that makes setting up actions such as clearing a room full of enemies a refreshingly simple task. Even more impressive is the cover system, which is a joy to use. Hold the left trigger and you duck behind the nearest object or wall, depending upon the way you are facing. Move the analogue stick in any direction and you peek out to take down any nearby threats. Sprinting is mapped to the left bumper, which makes running and diving for cover a wonderfully fluid single motion.

The AI makes the experience even more enjoyable. Your team are remarkably sharp, to the point where you will sometimes curse them for stealing a kill! Some nannying is still required, but they never wander into the line of fire and are deadly when sent in to clear a room. If you don't want to risk it yourself then you can always rely on your plucky squad to dive in and take down any immediate threats. Ordered actions also earn you additional experience points, removing the inclination to become a one-man army. The experience system is simple and allows you to focus on the situation at hand, rather than scrambling to maximise points. In spite of this simplicity, it's use in unlocking new items and camouflage options it is still extremely effective.

The enemy AI is equally impressive, with terrorists showing a talent for adapting to any given situation. This is most clearly demonstrated in Terrorist Hunt, a game mode that sees you and up to three other players obliterating a specified number of targets within a set area. You can replay the same scenario multiple times and, with each repeat, enemy movements and tactics are different. Foes also exhibit considerable skill in flanking and taking cover - and you soon find out that their bullets are just as effective and damaging as yours.

As well as terrorist hunt, there are a wide range of multiplayer modes on offer, with plenty of maps and additional downloadable content available (Ubisoft are currently offering one new map for free over Xbox Live, with more to follow). The multiplayer side of the game is just as polished as the single player and co-op campaign, with enough locations to suit any game type, be it a free-for-all Deathmatch or the surprisingly tactical Team Leader mode, which forces a squad to work together to protect one of its members. If the team fails and their leader is eliminated then they no longer respawn and the pace of the game is significantly altered to a more stealth-based approach. As enjoyable as the single player is, the online arena is where you will spend most of your time, coming back for more long after you've played through the campaign (and probably occasionally dipping back in to the campaign for a co-op game with friends).

While it has been criticised for not moving on much from its predecessor, Tom Clancy's Rainbow Six: Vegas 2 is a solid standalone title and, despite a few small issues, it is a worthy addition to any shooter fan's collection. Thanks to its extensive range of multiplayer options and the fantastically varied Terrorist Hunt missions, this is a game with lasting appeal that will continue to offer new experiences long after the single player missions are completed.

Reviewed by Henry Osadzinski for AceGamez (All Rights Reserved).