Shadows of the Damned is batshit crazy. Quite literally, at times. In the rotten bowels of the underworld, checkpoints are signified by a one-eyed bat called Willy, who - when passed - takes a quick dump to mark your progress. Doors to new areas are adorned with the faces of grotesque babies, who must be fed brains, eyes and (spot the odd one out) strawberries in order to open. Your gun can talk and is called Johnson. When your health's low, you'll neck bottles of tequila, absinthe and hot sake to replenish it. At one point, you'll move between realms by crossing a bridge formed from a naked woman's body, literally walking across her nipples.

Traipsing through this dark and twisted wonderland, demon-hunter Garcia Hotspur embarks on a rescue mission to save his beloved Paula from the clutches of an eight-foot tall, six-eyed cannibalistic demon lord that goes by the name of Fleming. What follows is ten hours of slaying monsters, solving puzzles and going "eww" at particularly gruesome bits. This might sound like all the other horror action titles out there, but when the credits are decorated with the names of Suda 51 (Killer 7, No More Heroes) and Shinji Mikami (Devil May Cry, Resident Evil 4), you can bet there's something more to it all.

There is. The game is defined by a kooky sense of humour and Mexican undertones. Garcia delivers his foul-mouthed quips with a thick Meh-hee-can twang, whilst the soundtrack is spurred on by lively guitars and maracas combined with the occasional outburst of thumping metal, and the sinister imagery of the underworld. The game has a very distinct atmosphere.

The script is one of the game's crowning achievements, chock-full of delicious innuendo and self-referential humour. "He's an absolute lunatic!" Garcia comments on a particularly exuberant enemy. "Maybe he plays too many video games?" offers Johnson as an explanation, blissfully unaware of the irony. Shadows of the Damned never quite breaks the fourth wall, but it does give it a good kicking every now and again.

And yet, underpinning all this nonsense, there's something really quite grim about it all. Some of the things you'll witness over the course of the game - demons exploding out of the chest of your girlfriend, a boss battle where you have to shoot the swollen red testicles of a giant flying bird, a demon who wears the skin of young girl he murdered - serve as a harsh contrast to the comedy. But even if it's laced with guilt, you'll still laugh; Shadows of the Damned is up there with Portal 2 and Bulletstorm as one of the funniest games this year.

By the end of the first level, you'll have a Boner. The talking skull, Johnson, is your escort through the underworld and a faithful sidekick with more than a hint of Stephen Merchant about him. He also has the ability to transform into numerous objects. In addition to a motorbike and the torch Garcia uses to light the way, one of these objects is a gun that can shoot bones - the 'Boner'.

After upgrading Johnson with blue gems collected from the bloody corpses of VIP demons (bosses), you'll unlock more weapons: the Teether (which shoots teeth) and the Skullcrusher (which shoots skulls). Red gems dotted about the underworld can then be used to upgrade the power, capacity and reload time of these firearms, as well as Garcia's health. Staying alive on the harder difficulty settings requires a decent supply of said red gems.

Thankfully, these (in addition to ammo and drink) can be purchased from Christopher, a half-human, half-demon salesman who loiters around certain areas in the game. Whilst clearly a nod to Resident Evil 4's merchant, at no point during the game does he utter the phrase "got a selection of good things on sale, Stranger", which is upsetting. He is full of his own hilarious quips, however.

Blue gems unlock more than just new weapons - they have the ability to 'evolve' existing ones, too. After time, the Boner becomes the Hot Boner (which can shoot sticky explosive mines), and - later - the Big Boner, which Garcia wields shouting "taste my big boner!" whilst firing his load at giant demons in a one-off shooting gallery mini-game.

Darkness plays an instrumental role in traversing the underworld. Every so often, an area is submerged in a filthy purple haze, which will gradually deplete Garcia's soul meter. Restoring a more pleasant ambience to the area requires firing a 'light shot' (by tapping RB) at the mounted head of a bleating goat. Obviously. Often, however, the door to the next area can only be opened by flipping a switch that can only be seen (and indeed flipped) in the darkness. Variants of this puzzle are relied on throughout the game.

Shadows of the Damned boasts a pleasant amount of diversity. In Act 4, for example, the action is interspersed with 2D shmup sections, swapping the dark hues of the underworld with quaint cardboard cut-out visuals. While the change in pace is certainly refreshing, these sections can be sluggish and unwieldy.

Worse are the semi-frequent interludes where you have to run away from a demented, lingerie wearing version of Paula, who - should she get her hands on Garcia - will straddle him and plant a single kiss on his lips - a devastating one hit kill. As she gives chase, arms outstretched, you'll have to clear debris blocking the path and avoid oncoming enemies. She's always right behind you, however, so one small mistake and it's all over. It's not that these moments are badly designed, as such, it's just that these parts aren't fun and feel needlessly unfair.

The game has its fair share of technical difficulties, too. The camera has a hard time keeping up during more frantic altercations, often getting wedged between Garcia and a wall, showing a close up of a demon's chest or something equally as unhelpful. Collision detection is also a problem. Invisible walls (something that really bugs me in 2011) are everywhere, and projectiles - the Hot Boner's mines, for example - often pass right through an enemy. Technically speaking, Shadows of the Damned can be more than little frustrating.

The game coaxes out hearty chuckles and swear-laden outbursts in equal quantities, but there's no denying that the resulting blend of emotions make for a memorable experience. Shadows of the Damned is easy to criticise, but it's got character - brimming with the stylishness of Suda 51 and the maturity of Mikami. It's a cool game, and is likely to earn a loyal following despite its problems.