The Majin looks pretty intimidating in the wrong light. He's humungous, with arms like tree trunks and a frame that would put the Hulk to shame. Grass grows on his forearms and back, and two colossal horns sprout from his boulder-like head. One look at his face negates any sense of danger, however; his tiny glowing eyes emit only kindness, and the teeth living in the huge chasm of his mouth are round. Everybody knows nasty monsters have sharp teeth. No, the Majin is one of the good guys - a legendary guardian who wouldn't harm a fly. Unless, that is, you ordered him to.

Majin and the Forsaken Kingdom is a game that revolves around partnership. You could compare it to Enslaved, if you liked, or - more appropriately - Ico. The game is developed by Game Republic, a Japanese studio formed from several members of the original Ico and Shadow of the Colossus teams, so the comparison is just. While it seems to have flown under the radar of the entire industry, forty-five minutes with the game was enough to make me take notice. There's an atmosphere and charm to it that struck a chord with me almost immediately. It's cute, funny, intriguing and thoroughly enjoyable.

The story is traditional: an evil sweeps across the land, swallowing civilisations and plunging the world into darkness. The survivors band together, fleeing to the bordering desert to start the world anew. One day, the strongest of these survivors leaves on a mission to reclaim the land but is thwarted in their efforts by warriors born from the darkness. These creatures drip with viscous black ooze, the kind of monsters children might imagine lurking in the dark corners of their bedroom at night. One hundred years down the line, a lone thief manages to slip past the warriors unnoticed, and heads into the heart of the Forsaken Kingdom. This is where the adventure begins.

Our thief is an attractive blend of Jak (Daxter's pal) and a Gelfling (of The Dark Crystal fame). His competency as a hero is brought into question almost immediately, however. In a scrap against several shadow warriors, he manages to lose his sword and is thrown into the depths of a rather uninviting hole. Lying at the bottom of some dark and mystical ruins, the young thief is spurred back into action by the distant sound of snoring. Hoping that it will lead him to the legendary guardian that is said to sleep within its depths, he pushes forward. The music sets the mood fantastically; sitars and violins giving the place a whimsical feel. The snoring gets louder and louder, until the beast creating the awful din is revealed.

The Majin also looks as if he was born from the mind of Jim Henson; not for a second does the thief think the creature could do him any harm. After releasing the beast from his shackles, the unlikely duo decides to escape the desolate ruins they've found themselves in and return to the outside world. No longer a hostage of the darkness, the Majin declares our Gelfling-esque hero his new master and the seeds of a strange and compelling relationship begin to germinate.

The Majin carries out his new master's commands with child-like glee, smashing enemies to a shadowy pulp as if it were a playground game. He laughs and jeers, shouting his trademark 'yay!' every time he sends another one to the grave. He's obedient to a fault, and won't do anything without being asked. This, as you might imagine, gives rise to all manner of puzzles and combat strategies - you're the brains and he's the brawn. Often your path will be blocked by huge stone doors, which the Majin must be ordered to open in order to progress. Shadow warriors will hamper your advances at every turn, but with the Majin at your side there's little to worry about.

The thief can of course jump into the fray too, wielding the large steel pin that once held the Majin captive. There are even special finishing moves that see the pair attacking together, but the thief will struggle to down an enemy by himself. His talents lay elsewhere; in stealth, agility and cunning. Often you'll have to run off by yourself to pull a lever or collect an item, at which point hand-to-hand combat is a less than desirable option. Sneaking up behind an enemy and plunging your weapon into their back is a much safer (and more satisfying) approach.

By collecting glowing shards from the corpses of your fallen foes, you can increase the attributes of both yourself and your bumbling partner. Blue orbs increase the thief's health and stamina, whilst red ones - obtained by pulling off combos - will increase the friendship level between the two characters. Over the course of the game, the Majin will learn new moves and become even more lethal in combat, and the thief too can improve by equipping new pieces of armour collected throughout the adventure. The RPG stuff is basic, but helps develop the characters from the perspective of gameplay as well as narrative.

After escaping the dank depths of the ruins, the pair steps out into the bright colour-drenched world of the Forsaken Kingdom. Sitting under a tree, the duo finds some time to indulge in a little conversation - not that the Majin is very articulate. Still, he introduces himself as Teotl and asks that the thief reveal his name, too. The thief is unable to do so, however; like all too many protagonists, he's gone and lost his memory. A person without a name is too bewildering a concept for the giant, so he decides to name his master himself. "You Tepeu", he declares, and the pair shake on their belated introduction.

This triggers a flashback in the Majin's mind, shared by the young thief through the pin that once held the creature captive. In quaint 2D visuals, the Majin is seen protecting a young woman from hordes of shadow warriors. The friendly oaf is bleeding heavily; an assortment of arrows lodged into his back. He refuses to rest, though, and the scene fades out as the Majin continues to fight a seemingly hopeless battle.

Just who was the mysterious woman? Why was Teotl protecting her? Does she know anything about Tepeu's unaccountable past? These are all questions I'm looking forward to have answered, as well as seeing the relationship between the two protagonists blossom. Sure, the gameplay won't set the world on fire - the likes of Zelda and Ico have done what this has many times before, but there's a fantastically endearing quality to the game. It's in the atmosphere, the child-like innocence of the colossal Majin and the intrigue that quickly arises from a seemingly clichéd narrative. There's something very likeable about it.

With so many great titles vying for attention in the run up to Christmas, there's been a lot of talk of 'sleeper hits'. For me, Majin and the Forsaken Kingdom could well epitomise that phrase. Given that I hadn't heard a peep out of the title up until a few weeks ago, I was genuinely taken aback by it. The co-op mechanics are solid, so too is the AI, and you'd have to have a heart of stone not to fall in love with the Majin. Quite how a creature of his size has evaded the attention of the industry for so long is a mystery.

Majin and the Forsaken Kingdom is available for Xbox 360 and PlayStation 3 this winter.