What makes a good video game character? Is it personality, looks, abilities or dialogue? Is it quality motion capture and well-delivered voice acting? Or is it something less definable?

Between them our Top Five Characters of 2012 tick all of the above boxes, achieving greatness through one or more of these varied attributes. But perhaps even more interestingly, many of this year’s selection share one quality: they're bat shit insane. 

We've got psychopathic antagonists, an increasingly unstable protagonist and a degrading AI losing its grip on reality. Even the most sane of the bunch enjoys splitting skulls in half with a tomahawk, so maybe he's not so balanced either. 2012 was the year of the nutter.

Following in Altair and Ezio's killer footsteps was never going to be an easy task. Both characters became icons; unique ultra-cool frontmen to a multimillion-selling franchise that meant a hell of a lot to a hell of a lot of people. Yet somehow Assassin’s Creed III’s Connor managed it.

His real name, of course, is Ratonhnhaké:ton, the half-British half-Native American. What makes him such an interesting character is that he’s not defined not by his heritage but by his hatred of tyranny. Black and white in his morality, Connor knows right from wrong and isn't afraid of burying a tomahawk in someone's head to prove it. 

Plus he has a colon in the middle of his first name. You've gotta be pretty badass to pull that off.

Many videogame characters emerge from the end of their adventures exactly as they entered them. They may have just learned the secret of the universe, dodged death by millimeters and saved humanity from extinction, yet they rarely change.

But not Captain Martin Walker. Though he begins the campaign as a jobbing soldier, at the end of Spec Ops: The Line, he emerges (or doesn’t) a completely different character. We can't say much for fear of spoiling exactly what happens (or doesn’t), but it's safe to say that Walker’s experiences in post-catastrophic Dubai change him forever.

Spec Ops: The Line is a game that doesn't shy away from consequences. And while many games take their protagonist's mass-slaughter lightly, in Cpt. Walker we have someone for whom it is incredibly meaningful. And that's why he's one of the best characters in games this year.

Handsome Jack, the moon-owning narcissistic antagonist of Borderlands 2 is one of 2012’s most unique characters. Initially a nice bit of comic relief and an amusingly arrogant irritant, it’s not long before things take a dark turn.

By the end of the game Handsome Jack reveals himself to be an all-out bastard, one of gaming's most overtly evil bosses, a truly sinister piece of work. And that's the beauty of the character. Funny and uncompromisingly sadistic, he's one of the few antagonists you'll laugh along with but also want to hit straight in the nuts. Repeatedly. With a Hyperion Nidhogg rocket launcher.

He does own a diamond pony called 'Butt Stallion' though. Respect for that.

Some characters are bought to life by great voice actors. Some are brilliantly scripted. Others are well animated and situated within their worlds. Far Cry 3’s Vaas Montenegro is all of these things and more.

On an island of complete lunatics, Vaas is king of the psychos. He’s a completely unhinged nutjob whose lung-shredding, ultra-violent outbursts rip through his more reflective, quiet moments like a machete through a jugular. The thing about Vaas is that you never feel safe. He's a deeply unsettling character.

Yet somehow, despite this you may grow to like Vaas, in a strangely twisted way. He's utterly doolally, completely deranged and yet oddly charismatic. Whether you like him or not, Vaas isn’t a character you'll forget in a hurry.

While everyone else in our Top Five Characters of 2012 list are new, Cortana has been around for years, a cornerstone of the Halo franchise. We know all about her, and it’s this familiarity that makes the AI's story in Halo 4 all the more remarkable.

Previously an odd mix of TomTom navigation system, narrator and love interest, Cortana's character takes a dramatic left turn in Halo 4, as the tech that drives her breaks down and she becomes ‘Rampant,’ degenerating into anger, madness and schizophrenia. 

Helped along by some fantastic voice acting from Jen Taylor and some great writing by 343 Industries, Cortana’s fate is simultaneously frightening, heartbreaking and sorrowful. Piling all this into one character and making it believable is no easy task, but it’s delivered perfectly.

Making us look at someone we already know in a completely different way? That's why Halo 4's Cortana is a triumph fully deserving of our Best Character award. In a year overflowing with head cases, Cortana tops them all.