Assassin's Creed Unity: Dead Kings review

They say time heals all wounds, but Assassin's Creed Unity: Dead Kings opens with Parisian Assassin Arno still nursing his injuries and laying low, having left the French capital firmly behind him. Ubisoft's add-on acts as a coda to Unity's main campaign and - without wishing to spoil that - it's fair to say our hero is in a bit of a slump.

His mood is fitting of the Assassin's Creed series as it stands today. Unity, last year's major release and the first built specifically for PlayStation 4 and Xbox One, was a technical embarrassment for Ubisoft, whose executives were forced to publicly apologise to fans, cancel the game's Season Pass and instead offer Dead Kings for free. But even if it had launched without bugs, it was still unlikely to have found a place in fans' hearts alongside the seafaring fun of Black Flag or the high points of Ezio's Renaissance trilogy.

Poor Arno. His mood is reflected in the DLC's deliberately dour, downtrodden surroundings: the muddy, provincial town of Franciade where he plans to bargain his passage overseas. It's a dark place, its mists seen through an Instagram filter, and like Arno it has suffered through the destruction of the recent Revolution. Its foggy, muck-filled streets are a marked change from the bright, blood-soaked cobbles of Paris and while much of the architecture is familiar, a couple of environments stand out.

The town is dominated by a ruined cathedral whose half-standing remains Arno must dutifully clamber over in the game's first main mission. The burnt-out beams and broken-down walls are a neat metaphor for Arno's own condition, as are the now-robbed graves of former French kings which once lay at the building's heart. But as impressive as the location is, it is what lies beneath it - and underneath the series' usual map - that is most worth exploring.

Above ground there are three major districts to explore (the built-up Basilica, the rural Windmill and the expanse of the Cemetery), each of which is dense as an equivalent sector in Paris. But there are also three areas below the surface: the Catacombs, Quarry and Royal Crypt, which expand the map considerably. Dead Kings finally fulfils the promise of a fun subterranean Assassin's Creed adventure, with a network of Indiana Jones-style caverns, temples and quarries that stretch from one side of the map to another. (AC3 previously toyed with an underground section by including long, dull, maze-like tunnels, while Unity's Paris catacombs improved on that idea but served little purpose.)

Franciade's tunnels are home to the new Raider enemy faction, looters who will attack in huge groups if disturbed but who will run from you should you kill each of their squads' beefier, armoured leaders. This mechanic - and a lot of the underground's layout - encourage you to plan your path carefully. These things serve to push stealth as your plan of attack rather than blundering in all guns blazing. Although, if you did really do want to do that, then there's the new Guillotine Gun, a lumbering axe that also doubles as something like a grenade launcher, whose range will allow you to fell clusters of enemies at once.

But it's more fun to take targets by surprise, and simply navigating these underground areas will require more thought. A few sections require you to use a rather fiddly lantern item to ward off bats and bugs that block your path, but this is thankfully kept to a minimum. During story missions the lamp is also used for revealing puzzle hints, and a few situations require a bit of lateral thinking to progress. There's even a Zelda-like puzzle chime for when you solve particular secrets. Standout moments include platforming puzzles reminiscent of the Ezio-era Assassin's Creed entries, where whole rooms were turned into clever mechanical machines you had to leap and 'back eject' through to traverse.

The tunnels are also where you'll meet a new sidekick of sorts, a character named Leon whose relationship with Arno just about walks the line between saccharine and sweet. It is through this fresh character, far more than the return of a few faces from Unity itself, that Dead Kings provides proper closure to Arno's story, something that was left feeling a little unfinished after the main game's end. With a smaller canvas, Dead Kings' tale feels tighter, and free to be more personal than Unity's Revolution-spanning Assassins versus Templars theatrics. And while it doesn't redeem all of Unity's sprawling narrative mistakes, the guiding hand of Assassin's Creed: Brotherhood and Far Cry 3 writer Jeffrey Yohalem is noticeable long before his name pops up in the credits as Dead Kings' co-writer.

For anyone who enjoyed Assassin's Creed Unity, particularly those who may have thought about returning to the game more recently now its technical issues have been largely teased out, Dead Kings offers a good excuse to do so. There are at least six hours of extra gameplay to be had for those looking to unlock all of the DLC's secrets, and the quality bar is such that it is clear this add-on was once marked for paid release. There are a number of new costumes to unlock, plus more Paris Stories, Enigmas and Murder Mysteries mission types have been added for you to explore (or ignore). There are even a few Far Cry-style outpost missions, which involve you sneaking in to areas of the Franciade map without being spotted.

And that's not to mention the countless extra collectables and chests. Thankfully there are no new chests that require the game's companion app - which is a very good thing - and while some are designed to be unlocked through Ubisoft's Assassin's Creed Initiates online service, the developer previously turned this requirement off after the platform failed to remain online for any length of time (so all of these rewards can be opened immediately).

They say time heals all wounds, but free DLC can't hurt either. Dead Kings offers much for those still enamoured by the series, and its offering as a freebie is a fine gesture to anyone left aggrieved by last year's failings. Still, time will tell whether it - or what Ubisoft has planned next - can convince those who have been put off by the series' longer sense of stasis.