With four wholly distinct iterations in as many years, it's a wonder the Splinter Cell series has remained fresh since it debuted in late 2002. Yet Ubisoft and its stable of internal development teams have managed to imbue each of Sam Fisher's subsequent missions with unique and compelling gameplay mechanics. We spent some time with the campaign mode in the fourth game, Double Agent, and it looks like that trend will continue this year. Though we unfortunately haven't yet gotten our hands on a build of the Xbox 360 game--sure to be the flagship version when Double Agent hits in September--we were glad to see that Fisher is still alive and kicking on his original home, the Xbox.

　　Bald is beautiful, says Sam Fisher.

　　Initially there was a great mystery surrounding Double Agent as to whose side exactly Sam Fisher would be fighting for. By now, it's been widely reported that the game will see the famous Third Echelon agent infiltrating a terrorist group in his ongoing pursuit of great justice. Now, we've gotten a closer look at how the narrative will unfold over the course of the game. It seems the storyline will be told in flashback, as Double Agent starts with a call from Fisher to what sounds like a high-ranking official at the CIA, in which he defends his rogue actions against sharp criticism of his methodology. The game then sends you back in time to play through the original mission that began Fisher's undercover caper, and you'll flash forward to this phone conversation between missions as Fisher and his adversary discuss the events that have transpired.

　　This first mission has Fisher and a computer-controlled ally infiltrating a weapons facility in Iceland, before things have gone bad. So this is standard Splinter Cell fare, where you're proceeding through your required and optional mission objectives, occasionally taking direction and receiving updates from your old pal Lambert. But even within the first few minutes of the mission, new gameplay aspects became evident. For one, since this first mission sees you accompanied by a friendly operative, you can perform some of the tandem maneuvers that you could pull off in the cooperative mode of the last game, Chaos Theory, when you had a second player at the controls. You'll be able to boost your ally up to a high ledge, for instance, and then have him help pull you up too. Otherwise, this first mission features the same stealth action you've come to expect from Splinter Cell, including sneaking around guards, disabling lights and security systems, hacking into computers, and picking locks--basically, getting in and getting out without being seen.

　　Some of the co-op moves from the last game will now be available in the single-player, when you've got a computer-controlled ally with you.

　　At the end of this mission, though, the game drops a pair of story-related bombs. One, some bad guys have made off with the weapons you were after--though it turns out they weren't just any weapons. A cache of red mercury--a nigh-mythical, horrifically explosive chemical compound--is missing, and it appears it has fallen into less-than-savory hands. Needless to say, Fisher and Lambert aren't very happy about that. And then there's the fact that Fisher's daughter has just been killed, which he understandably doesn't deal with very well. In the face of frustrating government foot-dragging on the red mercury issue and a feeling of nothing left to lose, Fisher and Lambert hatch a plan that would let Fisher infiltrate the underworld group with access to the red mercury in order to save countless lives before things go awry.

　　It's at this point that the radical changes to Double Agent's gameplay become evident. You start the second mission in a penitentiary where the one contact who can put Fisher in touch with the right (wrong) people is being housed. Once you're on the inside, you can kiss all those typical Splinter Cell amenities good-bye. No night vision, no advanced modular assault rifle, no nothing--just your bare fists, your wits, and your will to succeed. Luckily, you'll start out having already befriended the man on the inside that you're looking for, so you'll have a partner in crime that you can work off of to rig your escape and meet up with the terrorists. From what we've played so far, this includes a lot of sneaking through secret passages within the prison and manipulating the guards and other inmates.

　　Mr. Clean called...ah, forget it.

　　In fact, one early cinematic sequence took us by surprise but showed us where Ubisoft is going with the game's design. When we took Fisher out into the prison courtyard, where he'd planned a diversion with his coconspirator, the other man started a fight with a troublesome inmate, at which point Fisher intervened with his famously gruff manner, and we were given the choice to kill the foe or merely incapacitate him. After we opted to silence him for good, we were presented with an onscreen meter that indicated, Knights of the Old Republic-style, our standing with both the NSA and the terrorist cell. (Naturally, killing bystanders will move your slider over toward the bad guys.) Ubisoft has stated in the past that the course of your game experience will be dramatically affected by your moral alignment, which is clearly the direct result of your in-game actions. We're interested to see if this claim holds true as the game wears on.

　　Of course, we'd prefer to get our hands on the Xbox 360 version of Double Agent, but we have to say the standard Xbox game is a pretty good substitute for the time being. The game looks just as good as Chaos Theory did, with all the same sorts of graphical niceties you'd expect to see (in fact, the visuals even have a qualitatively similar look to those of the last game). So far, we're more interested in the gameplay changes the designers have made this time around, which seem like they'll make Double Agent a decidedly different experience in some ways from the past three Splinter Cell games.