y now, Ezio Auditore da Firenze has to be the hardest-working man in video games. At the age of 52 he is still committed to saving the world and unlocking the secrets of the universe, during an era where most men entered their autumn years at 45 and died at the age of 59.

Not only that, the sort of activities required by Ezio's world-saving efforts involve parkour, sword-fighting and climbing up towering structures with no safety line attached. In light of his spry athleticism, it almost seems unfair that NPCs comment as often as they do inAssassin's Creed: Revelations that: "You'd think that behaviour would be beneath him at his age!"

Mind you, the odd ageist crack is pretty small potatoes when you consider the big picture in Revelations. Ezio's quest ultimately plays a part in how a barman in the 21st century called Desmond winds up trapped in a high-tech machine, which allows humans to share the memories of their ancestors.

The game begins with Desmond adrift in the Animus, with questions surfacing about the state of his body in the real world. He runs into a sarcastic bloke called Subject 16, a disembodied consciousness who informs him that the memories of Ezio and Altair have become too intertwined with his own. If he returns to his body before he finishes exploring them, he'll go into mental arrest.

To that end, he needs to follow Ezio into Constantinople in 1511 AD, as he searches for decryption keys left behind by Altair, that will allow him to learn the whereabouts of an item that could end the war between the Assassins and the Templars.

As convoluted as all of that sounds, in practice it's pretty straightforward. Players control Ezio for the lion's share of the game, jumping in and out of Desmond's and Altair's storylines at certain stages.

Most of the action takes place in Constantinople at a time when the Ottoman Empire is on the rise, and as a venue for adventure it holds its own impressively against the Renaissance and Medieval environments featured in the earlier games.

The streets buzz with market sellers, town criers and guard squadrons who patrol the cobbles. Head up above street-level and majestic spires and sun-kissed domes jut out against the undulating concrete rooftops.

As with every other city in the series, Constantinople is a joy to explore and its map is filled to bursting with activities. Players can still buy shops and businesses, kit themselves out with weapons, armour and equipment, hunt for treasure chests and hire the odd band of thugs or Romany women (standing in for courtesans) to run interference.

It almost goes without saying, because this is an Assassin's Creed game, that everything looks historically accurate and absolutely gorgeous to boot.

However, while the graphics remain a series strong-point, wrinkles and blemishes are beginning to become a little more pronounced in other areas. Over the last four main games – leaving aside the titles that appeared on handhelds and on Facebook – the gameplay has been tinkered with and augmented somewhat, but key flaws still remain.

The free-running control system is still twitchy, meaning the segments involving parkour are never as free-flowing as they should be – a problem the series has had since the first instalment.

Climbing has been improved over time, but the routes up towers and buildings aren't always clear. Sometimes the player is required to hit the jump button in order for Ezio to reach a handhold above him, but it's never clear when this is the case.

Hit jump at the wrong moment and Ezio will kick off the building in the opposite direction and crash to the street below (although the introduction of parachutes in Revelations softens the landing somewhat).

Perhaps the most baffling aspect in Revelations is the fact that the developers have remapped some of the controls. It's a small consideration, certainly, but long-time fans of the series may be somewhat irked when they instinctively reach for the parry command in every second sword fight, only to find they've left themselves open to attack.

We also lost count of the number of times we accidentally fired Ezio's flintlock at the top of a tower by pressing Y, having become so used to associating that button with the panoramic View Point animations in all the other games of the series.

Still, not all the changes are bad. One of the first and best new additions in Revelations is the Hook Blade, which replaces one of Ezio's concealed blades from the last two games. In combat, it gives Ezio a couple of options aside from basic melee; it can be used to trip up opponents, or as part of an evasive move in which Ezio flips over their back and leaves them sprawling in the dust.

The Hook Blade also comes in handy in Ezio's rooftop travails. By hitting B mid-jump, the player can extend Ezio's reach, allowing him to jump over greater distances between rooftops, and reach ledges that are higher above him on vertical climbs.

There are also a number of ziplines throughout Constantinople and Ezio can slide down them using his Hook Blade, and even, if the player times it just right, leap off and assassinate any enemies Ezio is sliding above.

On top of that, Ezio now has the ability to craft a variety of explosive devices ranging from smoke bombs that detonate on impact, to bombs which shower the ground with fake coins when they explode, to good old fashioned stink bombs that leave opponents briefly dazed.

Players will find casings and ingredients for Ezio's bombs in shops and treasure chests dotted around the city, and in the pockets of guards they've killed. They can then make bombs at crafting tables at the local assassin's guild.

Ezio can still recruit assassins to his cause, as was possible in Assassin's Creed: Brotherhood – and, once again, he can train them up to Master Assassin level by sending them out on missions in faraway lands. Ezio can also still deploy assassins as a distance attack, provided they're all not overseas poisoning someone.

It's worth levelling all Ezio's assassins up as Master Assassins can be put in charge of Guild Headquarters, which protects them from attack. This, of course, takes quite a bit of time to do, so in the meantime, players can prepare themselves for a series of tower-defence games.

Throughout Constantinople, there are towers that are under the control of the Templars, the Ottomans and the Byzantines. Not only does this make the areas around them rather dangerous, it prevents Ezio from buying up businesses and earning cash.

To seize control of these towers, Ezio has to identify the local leaders (or leaders), kill him (or them), and then set the tower on fire (in a manner very similar to the way he took control of the Borgia towers in Brotherhood).

At that point the tower becomes a Guild HQ, and until it has a Master Assassin installed it's vulnerable to attack. When this happens, players have to win a tower defence mini-game, in which they place blockades in the path of oncoming soldiers and place assassins on rooftops, who rain down arrows and musket balls. They also have a larger attack in the form of a cannon, which needs to recharge over time.

While the tower defence game is enjoyable for the most part, towards the end it starts to eat into the proceedings. Annoyingly, while it's presented as an optional side-quest, it's actually necessary to capture all the towers in order to progress through the game easier.

Players that don't bother with it face an uphill battle as without Guild HQ's, they can't recruit assassins, guards recognise them more often and businesses are locked away from them. After a while, the notification that a Guild is being attacked becomes irritating, as it usually interrupts a more fun and worthwhile activity – like picking the pockets of NPCs, for example.

Overall, it feels a lot like the multiplayer mode in that, while neither is bad, they do seem a little unnecessary in an open-world game, which is largely story-driven.

It's in the plot where Assassin's Creed: Revelations shines the brightest. It's story may be madder than a bag full of spanners, but it's populated by colourful characters, chock-full of interesting and amusing events and the way it unfurls overall is simply magical. And holding everything together at the centre is Ezio Auditore, one of the most engaging and best-written characters in gaming.

While Assassin's Creed is strictly speaking Desmond's story, and Altair featured before we made Ezio's acquaintance, players have spent more time with the Florentine noble than any other character in the series.

We've seen him evolve from a young Lothario into a stern man of action, shared his losses – both familial and social – and guided his blade in quests for both revenge and knowledge. Without giving too much away, his tale in Revelations is one of the series' best and certainly worth exploring.

In fact, Ezio Auditore is, simply put, the only reason one needs to pick up a copy of Assassin's Creed: Revelations. While it doesn't feel like the step forward for the franchise that its two predecessors did in their day, Revelations can confidently stand shoulder to shoulder with the better titles of 2011.