We haven't gone far off AC 2's beaten path quite yet. Where the sequel had continued to push its Dan Brownish narrative toward its final denouement, Brotherhood extends it a tad longer. Or it extends Ezio's participation in the plot, anyway. And so we're back in Italy, just where we left off in the last game.

AC: B's main conceit is in establishing the Brotherhood, which is the most obvious change in the series. Now a Master Assassin, Ezio is in the throes of reorganising the entire order to fight against the Templars in Rome, and new members are recruited by completing missions scattered around the city.

Past instalments had you buying off citizens to help you with your task - you'll remember the happy prostitutes who you'd throw a shilling at to get them to shimmy around you, shielding you from passing guards. And, generally speaking, the Brotherhood is what would happen if this little bean of an idea grew into a fully-formed management system.

A few trailers have already shown what they're capable of, functioning as a kind of special attack used against nearby enemies: select a guard, whistle, and any free assassin will drop from as rooftop to take him out. However you can also level them up, customising their appearance and weapon loadout, by spending skill points earned by doing things such as sending them across Europe to fulfil their own assassination missions.

Whether it's particularly necessary to have an entire brotherhood backing you is a question not fully answered in the demo. Back in the days of AC and AC 2 enemy AI had the tendency to queue up to fight you. AC: B is admittedly cleverer with its AI, and so the pacing of combat has an entirely different rhythm. Where Assassin's Creed 2 emphasised counter-attacks, Brotherhood's mantra is "strike first, strike fast". You'll often have two enemies attacking you simultaneously, and likewise you can come at them with a sword in one hand and a hidden gun under your sleeve to deal with stragglers. Ezio is built to handle himself. Even with a sword alone he uses a basic kick-and-stab strategy: kick the nearest opponent so he staggers backwards, giving you enough time to stab the second nearest, and so on in a chain.

So while the brotherhood itself is the obvious shift, the most important change is the actual pacing of the game. The most common complaint of 2 had been the slow-and-steady introduction. I seem to remember meandering behind Veronica Mars for ages just to exit the Abstergo facility at the beginning of the game. On the other hand, within the period of 12 Brotherhood minutes Ezio has already had sex, had a cannonball eradicate his bedroom wall, ridden on horseback through a crumbling Rome under attack by cannons and footsoldiers, pulled himself up a wall and single-handedly took out most nearby enemies by wielding nearby cannons against them.

While the plot itself is still somewhat vague you're essentially playing the logical extension of the last title, the assassin who has mastered his craft and now seeks to go on the offensive against the Templars.

A few things about Rome. It's enormous, three times the size of the last game's Florence. It's also a patchy mess, stuck under Templar rule. Due to their corrupted decree Rome has essentially come apart at the seams, putting you in the position to invest in the rebuilding of the city in a similar fashion to your treatment of the village of Monteriggioni in AC 2. The area also appears to function as your new hideout in the 21st century - Veronica Mars' Scooby Gang of friendly 21st century assassins have run to the shelter of Italy.

Within the first hour and a half of hands-on gameplay the Desmond plot appears to have more meat to it than it did in previous titles, largely because aspects of Ezio's mechanics have been adapted more fully for Des. You'll take Lucy and vault her off your arms to reach a higher platform, or crawl Ezio-style up a wall to unlock a bridge. From the little specks of this that were shown, the Desmond segments seem to be in opposition to the free-roaming aspects of Ezio's storyline, however it's still a much meatier portrayal of the Des gang.

If the previous games set up a living, breathing historical city then brotherhood homes in on the systems at work inside. Is your brotherhood just a tool in a similar way to the interactive city dwellers of the previous game? Well they're similar, but different; the brotherhood is a broader interpretation of what's been offered before. Your fellow assassins are slightly more complicated than the meandering droves of AI prostitutes. They have more functions, and more individual characteristics. Whether the Brotherhood will offer more to gameplay than any other interactive NPCs is another story, but working in a team seems to give the game more scope than it has ever offered previously.