I remember when Sam Fisher was a good guy, the kind of hero you could take home for tea with your mum - provided that she wasn't some form of international terrorist. Nowadays he's one of those morally-ambiguous Jack Bauer types; you'd still call him a hero, but largely because he'd snap your arm off and force the wet end through your face if you called him anything else. He's mad, bad and dangerous to know.

We learned this lesson during our first encounter with Splinter Cell: Conviction, back at E3 in June. Since then we've gone hands-on with the game, but it's only now, with the advent of the Tokyo Games Show, that Sam has emerged from the shadows once more. While Ubisoft's premiere showed Mr Fisher hotly pursuing the man who killed his daughter, this second demo finds him dealing with a larger, far-reaching conspiracy. The exact details of this threat have yet to be clarified, but it has something to do with a possible EMP (electro magnetic pulse) attack on Washington. At any rate, it's a decent excuse for Sam to sneak into a military base, murdering dozens of people as he goes.

The demo kicks off in fairly classic stealth fashion, with Fisher creeping along a road outside a fenced-off compound at night. As he nears the entrance to the base, he ducks behind a crate - while crouched, Sam will automatically stick up against any suitable object. This handy cover affords an opportunity for a bit of eavesdropping on the nearby guards, but sooner or later the player has to go on the offensive. How you do this is up to you: you could use one of your gadgets, grab a guard to use as a human shield, or just stand up and go Rambo. Naturally, the latter is a risky strategy, and my clumsy efforts had all the military prowess of a blind man with kippers for hands.

Happily, Ubisoft's Alexandre Parizeau was on hand to show me how it should be done. With casual skill he snatched one of the guards and used him to soak up a few incoming rounds before neatly returning fire with lethal precision. After dumping his meat-shield, he then skulked off into the shadows, triggering the game's new Last Known Position mechanic. Since the last remaining bad guy was now unaware of Sam's location, he focused all his attention on the last place he'd seen him - a spot now represented by a ghostly white outline. As the panicking guard blasted away at nothing, Parizeau carefully flanked him and then snatched him from behind. Time to ask a few questions.

As anyone who saw the video will attest, the bathroom interrogation scene was one of the best bits of Conviction's first appearance at E3: a gleefully violent interlude that saw Sam beating seven shades out of some poor bloke in a public toilet. This second "discussion" was carried out in exactly the same way: the player drags their victim over to an object of interest and then hits a button to make Sam do his thing. The animation here is particularly brutal - you'll see Fisher knee his new friend in the balls, kick his legs out from under him, and smash his face against a wall or nearby vehicle. Eventually the guard will tell you about a scientist inside the base - someone who's going to be snuffed out as soon as the bad guys have finished whatever it is they're doing. In a last effort to get even, the soldier then attacks Fisher with a knife. Bad move. Same takes the knife and stabs the thug through his hand, nailing him to a tree stump.

Sam's shrine to Girls Aloud was coming along nicely.

At this point, the demo branches out a bit. There are at least two ways to infiltrate the base - through the front door or via a nearby drainpipe - but however you get in, you'll have to deal with a large group of armed guards. The villains seem to be testing some form of large EMP device that's hanging from the ceiling, and with a careful shot you can send this heavy machinery crashing down upon the men below. Needless to say, doing this will cause your enemies to swarm all over the place in search of you, and once this happens you'll have quite a battle on your hands. In case you'd forgotten, this is the new, faster, nastier Splinter Cell: kill or be killed is the order of the day.

Luckily Sam has a number of lethal toys at his disposal. At the start of the game he's just a crazy ex-spy, forced to rely on the tools he finds - like the piece of wing-mirror we saw in the E3 presentation. However, as time progresses you'll also find a number of other devices, many of them familiar. Nightvision goggles make a return, but this time they have an extremely cool sonar ability that allows you to see enemies through nearby walls. In my last preview I mentioned that the sticky camera is back, but I forgot to add one important detail: you can use this gadget as part of the new mark-and-execute system, the feature that allows Fisher to pre-assign targets and then wipe out several enemies in one go. Once you've charged this ability by performing a close-combat kill, you can single out multiple enemies for death using the RB button on the 360 pad; as soon as the enemies are in range, you just hit Y to kill everyone in a single, fluid motion. The number of foes you can target varies from weapon to weapon, but apparently you'll be able to boost this figure via some form of weapon customisation - Ubisoft won't give up the details on this yet.

In any case, the point is that the sticky camera now has an added layer of usefulness, since you can chuck one into a room, mark the thugs, then dash in and gun them down. Parizeau explained to me that the team wanted to make Sam's tools more gameplay-focused in terms of the way they're used. In the past, you'd just use the goggles when you were in a dark place, then you'd switch them off when you were out in the light again. Now, thanks to their sonar power, they'll help you to form your battle strategy.

Parizeau certainly knows how to use these devices, too. While my performance in the demo was remarkably clumsy (hey, I was rushing through it), he gracefully glided through the stage like a swan trained by the SAS. He cleared the main room in a matter of seconds, hurtled through the facility and down into some form of sewer, shimmying up pipes and crawling through vents at speed. There's no denying that Conviction has a swifter pace than its predecessors, and it's certainly easy on the eye. The lighting effects are particularly atmospheric, providing plenty of sinister shadows for Sam to skulk around in, and while you're hidden the screen takes on a grainy appearance - a subtle and stylish way to indicate that the player is safely hidden.

As I said earlier, the animation is also particularly elegant in its violence. There are quite a few controls to keep track of, but once you master them you'll revel in showing off as you despatch your opponents. At the close of the demo, I watched Parizeau as he silently crept up on a trio of unfortunate guards. A small metal cylinder suddenly landed by one of the guards' feet. "What was that?" he cried. A second later, the flashbang blew. A second after that, the three men were on their backs with bullets in their head. What was that, you ask? That was Sam Fisher, pal, and early next year, he's coming to get you.

Sam Fisher is coming to get you, if you have a PC or Xbox 360, in the first quarter of 2010