It's probably the biggest video game poster ever. Adorned across almost an entire side of the Los Angeles Convention Centre, home to the madness that is E3 2009, is Ezio, star of Assassin's Creed 2. His face is half concealed by a white hood. Both of his arms are outstretched, two, two hidden knives clearly displayed. It is as if he is greeting the thousands of attendees with a hug. It's as if he is almost smiling, smug in the knowledge that the game in which he stars will probably outsell almost everything else that's being shown inside the huge building.

Truth is, 2007's Assassin's Creed, released for the PS3 and Xbox 360, sold millions. Over eight million in fact. It lays claim to being the fastest-selling new IP ever. In short, it was a huge success for Ubisoft. All this despite it being a bitter disappointment for the vast majority of gamers. Why? Some found it repetitive. Some found the combat boring. Others slammed it because Altair couldn't swim. The inevitable sequel looks set to right those wrongs. Including the swimming.

Ezio, unlike Altair, can swim, as we found out in a personal behind closed doors demo of the game at Ubisoft's E3 2009 booth. He can swim with glorious abandon in the lakes of Venice, and, hush hush, two other 15th century Italian cities in which the game is set. He does it primarily for stealth reasons, rather than to get a dash of exercise. But he also does it because it affords him the opportunity to do what Desmond, the descendant of history's greatest killers and again the real star of the show, does best: assassinate people. From the water he's able to do it, sticking his dual hidden knives deep into the skin of unsuspecting victims. Then, like a silent but deadly submarine, he can swim off as if he'd never emerged. The addition of swimming shows that Ubisoft Montreal is aware of the criticism the first game received in spades.

It begins in 1448 Venice. The sky is black with night, save for the occasional firework. Ezio is sitting on a bench with two thieves, whom he has curried favour with in a previous side mission. A carnival is in full swing in the background. People are dancing in traditional Italian fashion, with masks and extravagant dress. A guard, though, knows something is up, and approaches the bench. He recognises Ezio, and begins to challenge him. With the push of a button, Ezio sticks a hidden knife into his body, and in one smooth motion he lowers the guard's limp body onto the bench to take his place, the thieves propping him up to conceal the act. Then he casually walks among the dancers, mingling, unseen. This is no fancy FMV trailer. This is Assassin's Creed 2 running in-game, in real time.

You can now swim

Ezio is in town to kill Carlo Grimalde, a powerful Venetian who murdered his family. It will be no easy task, not just because of the guards he employs, but because he's holed up in an impenetrable building. Thankfully, Ezio's got a mate to help him out, an incredibly smart mate to boot. Leonardo Da Vinci, no less. He's left a present atop a tall tower, one that'll help with the assassination attempt. We see Ezio climb the city buildings in glorious fluidity, much like Altair did in the original. He leaps from brick to brick and swings from poles as he gradually inches his way upwards. At the top of the building, the entire town is visible. The draw distance is jaw-dropping. The detail and colour of Venice, complete with real life buildings brought to life with the aid of a historian architect, is in full view. It's a stunning vista, and what Assassin's Creed is all about.

Next to him is Da Vinci's Flying Machine, a contraption the great man drew in real life but never realised. In the game, however, you get to take it for a spin. Ezio climbs on board the primitive glider, lines up a leap off the tower and takes a run and jump. He slowly glides down naturally, but is able to speed up by changing the position of his body. Hot air from fires lit by his thief friends during a previous mission provide lift in a fairly unrealistic way, lending the game an almost platform feel as Ezio bounces from red fire to red fire just to stay aloft. He lines up to fly directly through enemy guards, outlined in white. When he does he's able to kick them mid-flight in a fluid motion. The glider crashes in a ball of flame, but not before Ezio is perched above the high walls that protect Grimalde. Night turns to day as the day/night cycle flexes its muscles just for the demo. Ezio is in.

Combat seems similar to the previous game

Grimalde knows he's coming, and shouts in defiance. Ezio leaps onto a guard and sticks a knife into his body - an air assassination. Ezio attacks two guards stood near each other. The blades that so confidently adorn the LA Convention Centre flash into flesh at exactly the same time. Welcome to dual wielding. He's still high up above the courtyard though, so takes a leap of faith, a fan favourite from the original. Ezio plummets to the cobbled courtyard, landing in a straw cart. He's not safe though: a guard snuffs him out, but before he can blink Ezio assassinates him from within the cart with a single, deadly flash of steel, throwing the body into the straw as he gets out.

Now we see combat, much improved this time around to add variety. Ezio is able to disarm his foes and use their weapons against them. He disarms one guard of his spear, then impales him on it - the body slowly slides down the vertical metal pole as he goes to work on the next guard. It's wonderfully fluid, based on carefully timed counter attacks, as before, but with many more options. Ezio seems more powerful, more able to do serious damage with his fists compared with Altair.

All that's left is Grimalde, who begs for his life. It's no use. Ezio kills him, and the entire scene collapsed with a virtual reality simulation effect before reforming. More guards turn up. Ezio throws a smoke bomb, a new weapon bought at great cost, to stun the group before making his escape. There's no where to go, though, except in the water. This is where our demo ends.

It's clear, even from this brief first-look, that Assassin's Creed 2 is going to be a better game than its predecessor, not least by virtue of Ubisoft Montreal reacting to complaints from fans. There's more variety to combat; the 15th century Italy setting is less bland; you won't have to go through repetitive intel gathering before an assassination, and, perhaps best of all, you can swim.

Flight is one of the new gameplay mechanics

Still, Assassin's Creed 2 is very Assassin's Creed. The fighting works much the same. The graphics won't drop jaws quite like they did in 2007, despite being improved. The three city structure has been retained, as has horseback travel between them. And, of course, simply exploring and climbing and doing all that crazy acrobatic stuff will be wicked fun.

As you'd expect many questions remain unanswered. What, exactly, is going on with Desmond? In the stunning FMV shown during Microsoft's E3 2009 press conference, Ezio is clearly seen assassinating someone with a gun. We're told you'll be able to buy guns, as they were around during the time period in which the game was set, but, like smoke bombs, they will be expensive luxuries. When you fire a gun in Assassin's Creed 2, you'd better not miss. From what we've seen of the game, you'd better not miss that, either.

Assassin's Creed 2 is due out for the PS3, Xbox 360 and PC on November 17 2009.