What's the worst thing that can happen when you're frolicking about in bed with an attractive lady friend? In fact, don't answer that, because I can already tell you're thinking along the wrong (sexual) lines. No, the worst thing that can happen in such a situation is having a cannon ball fired through your window by a ten-thousand strong Templar army who want nothing better than to bury you neck-deep in rubble. This, incidentally, is the exact problem facing Ezio Auditore at the start of Assassin's Creed: Brotherhood. Poor guy. He takes some time out of his busy killing schedule to enjoy the company of a woman, and there's a full blown war going on outside his front door. No rest for the wicked, eh?

The opening scenes of Assassin's Creed: Brotherhood see Ezio scrambling across the rooftop of a villa as thousands of soldiers exchange blows in the streets below. The faint sound of cannon fire is soon confirmed by thunderous explosions overhead, as parts of the renaissance architecture come hurtling down from the grey heavens above. It's an explosive opening to the game, and a stark reminder that Brotherhood is a fully fledged sequel, and not some ambiguous spin off trying to cash in on the Assassin's Creed name.

As Ezio takes a moment to scan the horizon, the camera pulls back to reveal the sprawling city of Rome. Where previous games in the series took place over multiple environments, Brotherhood is set exclusively in Rome. Worry not though; although the action has been condensed into one location, the game still feels suitably epic. I was assured that Rome is three times as big as Florence from the previous game, which in itself was pretty sizeable. With the gameplay concentrated into a single area, the action remains focused, and the tension and pacing is controlled to a higher standard. Both of these facts can be seen first-hand in the E3 demo.

After being caught off guard by a particularly well placed canon ball, Ezio is flung from the relative safety of the rooftop and onto the street below. Regaining his composure, he proceeds to fling himself off a second rooftop (on purpose this time) and onto the back of a helpfully placed horse. Strangely, Ubisoft has improved the quality of these horseback sections by actually taking control away from the player. If you think about it, this actually makes a lot of sense. Horses aren't like cars; they're living beings that act based on their own instincts. Obviously the player needs some control over the beast, but by placing a greater importance on the horse itself, movement feels far more natural.

Combat and acrobatics have been intertwined with riding to a much greater extent this time around too. As Ezio weaves through decaying streets of Rome, he picks off enemies with his bow and eventually leaps from the animal mid-gallop to re-ascend the battlements. After an impressive display of athleticism, Ezio eventually reaches an unmanned canon at the top of the battlements. By taking control of the contraption, Ezio fires on the swarms of enemies milling about below. Ubisoft described this as an 'exotic' mission; a memorable set piece that takes players out of the usual Assassin's Creed experience. One of the fundamental problems with the first game was a lack of variety, and although this problem was resolved in Assassin's Creed 2, creating a diverse experience is still of the utmost importance with Brotherhood.

It wasn't long before Ezio found himself surrounded by Templars, and the demonstration's first combat scene unfolded. Ubisoft takes pride in the fact that they listen to as much feedback as possible, and a common complaint that came out of Assassin's Creed 2 was that combat felt uninvolving. In response to this problem, Brotherhood has actually been made more difficult from a combat perspective. Enemies no longer wait to be attacked, and won't hesitate to throw themselves into the fray. The player is urged to take an offensive stance; to 'strike first and strike fast', and a much greater importance is placed on successfully blocking attacks and incorporating them into your combos. In the demonstration I saw, the Ubi rep racked up a combo nearing double digits, a feat simply not possible in previous games.

So, all in all, the new features are very nice, but do they really justify the development of a whole new game? Probably not. Thankfully, the game has one more trick up its sleeve, and it's a trick that defines the very concept of the game. In Brotherhood, Ezio has reached a legendary status. Among other assassins, he's an idol; a merciless killing machine feared but respected throughout the lands. As a result of his iconic status, Ezio can find and recruit impressionable young assassins to join his cause. At the heart of this feature are some fairly in depth role playing mechanics; Ezio can send the fledgling assassins off on missions where they earn experience and level up. Once they've reached a certain level, they can be called upon in game to do Ezio's dirty work. With a fully functioning brotherhood at his disposal, there's no need for Ezio to lift a finger.

The single-player is just one facet of the overall experience; Brotherhood allows players to plunge a knife into the back of other human controlled assassins. Indeed, for the first time in the series (if you exclude the crappy iPhone game) the main menu plays host to a multiplayer option. Here, the assassins that form the Brotherhood forget their allegiances to one another, and become instruments of multiplayer murder. It's an alluring prospect, but Assassin's Creed wasn't originally designed with multiplayer in mind. Just how effectively does the game bring together multiple players? With a lovely Ubisoft PR person to chaperone me to the front of a very long queue, I decided to find out.

Sitting down with seven other wannabe assassins, I was greeted with a short tutorial for a game mode entitled 'Wanted'. The object here was simple: to assassinate a specific target whilst avoiding being assassinated myself. The problem (and solution, depending on your situation) is that countless AI clones of each character wander about the city, meaning that finding the 'real' target is no easy task. A compass at the bottom of the screen will gradually lead you in the right direction, but if your target has decided to blend in with other characters of his ilk, then it's nigh on impossible to work out who you need to kill. A good assassin will train their eyes for giveaways; running in public, climbing up walls, changing clothes. All of these actions stand out like a sore thumb to any pursuer, and if spotted, they won't think twice before slitting your throat.

Often a target will notice your presence before you deliver the fatal blow, and they'll inevitably make a run for it. Once they start running, the calm and collected style of play maintained up until this point is thrown out of the window. The chase is on, and your target needs to be caught before they slip out of sight. If you're quick enough, all it takes is a quick tap of the assassinate button within range to put some points on the board. Each character has their own unique skills they bring into the game, such as knives, smoke grenades or disguises, but these should all be used as a last resort. If you're good at the game, nobody will even notice you're playing.

Assassin's Creed 2: Brotherhood is a fantastic stop gap on the way to AC3. It might seem like the game is merely a testing ground for multiplayer, but the brand new storyline and extensive Brotherhood features suggest otherwise. The range and quality of the upcoming multiplayer modes will likely play a huge role in how successful the game turns out, but from what I saw at E3, Assassin's Creed fans have every reason to be excited.

Assassin's Creed: Brotherhood is out winter 2010, for Xbox 360, PS3 and PC.