The original Assassin's Creed has clocked sales of around 10 million units since its 2007 release; an impressive achievement for a new intellectual property. It's easy to see why the game was so popular, as it provided owners at the time with a justification for owning a HD console, during a period where many releases were starting to feel a little safe. It wasn't perfect by any stretch of the imagination, but then, it wasn't just a PS2 game with sharper graphics either.

Play ACII for 2 hours and you could be forgiven for thinking little was altered in the interim leading to its 2009 release. Play for 2 weeks however and exposure to a host of small but meaningful improvements, as well as generally more intelligent, adventurous design, will leave you in no doubt that the series has found its feet with this instalment.

As with the first game, ACII runs with an interesting, dual-strand narrative. The story sees Desmond Miles being sprung from confinement within the sinister, high-tech Abstergo Industries, before going into hiding with a small band of allies. Desmond's ancestors were assassins, and through a virtual-reality machine known as the Animus, he (and therefore the player) is able to relive their exploits, with the hope of shedding light on centuries-old conspiracies and what it is Abstergo are so desperate to find. Though something of a scientific leap-of-faith, the "genes with memory" trope offers plenty of gaming potential and narrative intrigue. The modern day bits have perhaps wisely been scaled back (amounting to no more than 1-2% of the play time) to offer further emphasis on the main meat of the game - what takes place in the Animus.

This time around you're following the Florentine Ezio Auditore, in 15th Century Renaissance Italy. The move to focus on a new lead protagonist immediately pays dividends, as though Altaïr was a solid hero in the crusades-set original and its portable spin-offs, the absence of a backstory or a broader, personal focus left him feeling more of a bit-part player than Ezio. Following the Italian nobleman's life from free-spirited teen to a forty-something assassin, his highs and lows are as grand as they are empathetic, and that the missions are significantly less mercenary in their nature than in the first game is a big plus too.

The game mixes open-world adventuring with elements of free-running and climbing, not dissimilar to the likes of inFamous and Prototype, only in this instance, it's not superhero antics you're getting up to, but the subtle art of stealth. It's accomplished stuff, with several tweaks enhancing an already-promising setup. Streets are bustling with market-holders, carnival performers, musicians, monks and courtesans all doing their own thing, there's a real sense of community - there's even the odd thief who'll pilfer your cash, forcing you to give chase. Braving the rooftops is usually the quickest method of getting from A to B, but attracts the attention of archers so it pays to be fleet of foot, though should you wish to be more methodical, you can hide yourself among the crowds. Ezio's is rewarded for inconspicuous behaviour; remaining "Incognito" ensures the city guard won't bat an eyelid, but should he become "Notorious", they're constantly on the lookout. Tearing down wanted posters and bribing heralds are two ways of reducing visibility, and because it isn't too fiddly or obtrusive, the whole idea complements the adventuring quite nicely.

Combat has been improved too. The original was weighed-down by frequent onslaughts that lacked finesse; in part due to the one-button attacks which lead to some protracted and tedious skirmishes. Whilst still relatively simplistic, the swordfights in ACII are less repetitive and place greater emphasis on blocks, counterattacks and the utilising of various cool pieces of kit Ezio attains. There's consequently lots more freedom; you can sneak up behind a guard and nick him with a poisoned blade; retreat out of sight and watch as his frenzied last moments act as a perfect distraction for the other guards. Meanwhile, there are less lethal ways of diverting attention from high security areas, namely hiring courtesans, who will help you blend in with the populous, and then can be instructed to distract specific guards. Smoke bombs are great too as they can aid your escape (or make taking out several guards significantly easier), and irritatingly persistent troubadours hindering your tailing of a target can be shaken off by throwing money on the ground. Almost without exception, these tools are great, because should you find an effective method in which to use them, their effect is both extremely satisfying and tangible thanks to the smart and receptive A.I.

Visually, there's little difference between this and the original, meaning that ACII looks just a touch dated. This is only in the most mercenary sense of the word however, as to ignore the sheer aesthetic beauty and intricate detailing of Florence and Venice in particular would be to do the game a disservice. It's still a thrill to climb hundreds of feet up a tower so as to see the awesome panoramic vistas of the city below, even if they are sometimes accompanied by a thin layer of fogging. Character animations look a little long in the tooth, but the overall presentation is supreme, with the white-washed menus in particular proving absolutely dazzling to behold.

There's always something to keep you occupied. Monteriggioni acts as a light business element allowing you to invest in the small city with the pay-off being cheaper prices and a better selection of weaponry and items in stores. It's a simple but rewarding idea, granting you a quantity of florins twenty minutes proportional to the value of the area. A particularly excellent feature that is rarely touched upon is the game's cross-connectivity with PSP spin-off Assassin's Creed: Bloodlines. For every boss you've slain in the portable version, you'll be rewarded with a version of their unique weapon in the PS3 game; a commendable bonus for those who've tackled both adventures.

As mentioned, the missions are far more engaging this time around. As well as the usual assassination, search 'n' find and scouting/following missions, there's a host of other adventures to undertake. The optional Assassin's Tombs are a real highlight. Typically based in sprawling cathedrals or catacombs, they reveal the full extent of the game's art design and platforming potential, mixing some gorgeous paintings and architecture with stomach-churning heights that often see you winding around a building and up into its wooden ceiling rafters. The tension when jumping on thin, rickety beams is palpable; you'll hold your breath for every one of them. Though this kind of concerted, labyrinthine design is not as apparent outdoors, they're absolutely brilliantly realised in the tombs, rivalling any of the modern Prince of Persia's for platforming nous.

There is inevitably still the odd peril caused by the controls, with Ezio occasionally jump off a rooftop in a completely unintended direction, seeing him lunge to his death. This isn't an issue that will necessarily be quickly fixed; the sheer number of interactive points on each building that can be grabbed and climbed is vast, so there are going to be times where the movement you instinctively believe Ezio is going to make is not what comes off. It's important to stress though that this is an occasional trouble, and the majority of the time the controls are very sturdily both on the deck and whilst climbing. Some of the cities don't allow for as instinctive a sequence of rooftop sprints as would have been preferable; Venice in particular, whilst a pleasure to explore, still causes frustration as you'll have Ezio hopping unceremoniously into the canals if you don't plan your routes.

At times enthralling and never less than engaging, the story produces a range of colourful characters that really bring things to life. Figures from history are brought to life in theatrical but powerful fashion, including the infamous Rodrigo Borgia as the chief antagonist, and the likeable Leonardo Da Vinci, who aids Ezio, not least by letting him test his prototype flying machine. The side-missions, which include beating up unfaithful husbands, racing around the rooftops and carrying out courier and assassination contracts are all of a decent standard, though it's curious that there's little incentive to tackling them, beyond a meek monetary reward for individual completion. They have no bearing on trophies or reaching 100% completion and as a consequence, leaves them feeling rather incidental. Fortunately, the story is more than worth the price of admission alone and should have you glued to Assassin's Creed II for a good couple of weeks. It's accomplished, addictive and marks a clear improvement over its predecessor - just what you want from a sequel, then.