Photographer Robbie Cooper is fascinated by the way that video games give players new identities – and his work captures these digital disguises. Simon Usborne reports

It was a boring corporate job that piqued the interest of the photographer and video artist, Robbie Cooper. "I met a company boss who was divorced and had bad access to his children," Cooper recalls. "So they met every evening in Everquest, an online 3D virtual world". Cooper asked the man what he and his children did as they carried massive swords around a land populated by fire-breathing dragons. "They talked about homework, their mother and school," Cooper says. "I was fascinated by the idea of this really banal but emotionally important conversation going on in this vivid fantasy world."

The encounter led Cooper to spend years on a mission to find, interview and photograph people for whom virtual worlds offer an escape or just a break from a real world into which they often struggle to fit. He trawled online forums and posted appeals for people willing to reveal their second lives alongside real-life portraits. Shot in countries including South Korea and America, his striking and sometimes surprising photographic juxtapositions will appear in a new exhibition at the National Media Museum in Bradford.

Cooper, a keen gamer but not a visitor to virtual worlds, started his project in 2003 with an idea of the kind of people he would find. "Back then this was very much geek territory," he says. Indeed, many of Cooper's subjects fitted the stereotype of the scrawny, pale-faced, sleep-deprived teenage boy immersed for 12 hours a day in his basement as, for example, a "barbarian berserker" wielding a spiked club axe.

But Cooper quickly discovered diversity in virtual worlds. The photos here include a Danish butcher reborn as a shaman, a Japan-born French journalist who created his avatar, Dark Freeman, in his own image only buffer, and a cigar-smoking machine gun-toting American ex-marine and former bounty hunter who becomes General Zondar, the pilot of an armoured space cruiser, when he isn't delivering gold bullion round Utah. And then there is Jason Rowe, a man from Texas with muscular dystrophy who can only move his thumbs.

"Before he discovered gaming, he was limited to watching TV," Cooper says. "Now he can go to bars and shoot monsters from his Imperial speeder bike." Rowe has met and become friends in the real world with people he met in the game Star Wars Galaxies. As he says in an interview that appears alongside his image and alter ego: "The internet eliminates how you look, so you get to know a person by their mind and personality."

As virtual worlds have grown and multiplied, they have become havens or just hang-outs for all sorts of people, and are moving out of the bedroom into the hearts of our homes. Ultimately, Cooper says: "We're all geeks now. Even Facebook is a virtual world and an interesting one because it's built not on anonymity but on vanity. When you're online constantly changing your profile picture and doing status updates, it's the same thing."

Robbie Cooper: Immersion is at the National Media Museum, Bradford from 12 March to 5 September.