Two years ago, he was a high-flying IT specialist for a leading bank. Then the young Scot was introduced to a life of adventure in the magical online land of Azeroth. Today Arklore - the "virtual name" by which he wishes to be known in this story - works for a fast-food restaurant.

At one stage, he had lost touch with reality to such an extent that he was no longer in contact with his father. Eventually the only way the pair could get in touch was for his father to use the computer skills of the gamer's young brother to create a character and send a message over the ether.

Stories such as Arklore's will be told this weekend in Second Skin, the first movie to seriously portray the culture of games such as World Of Warcraft, known as WOW, in which more than 50 million people take on the characters of wizards or warriors and join a struggle between humans and orcs in the kingdom of Azeroth. Once the stamping ground of lesser spotted virginal adolescents, the population of virtual worlds now almost matches Britain's.

Having worked his way up to be head of a "guild", Arklore now leads massive 40-person "raids", battles which the whole group take part in simultaneously. He said: "Sometime I would get home from work at five and play until three the next morning. I don't feel I've wasted my life, although I'd be lying if I said I hadn't turned down a Friday night out to go on a big raid. I once said that I would never avoid social situations for the game, but I did."

Both his mother and her new husband now play the game, although his father doesn't and has tried to talk Arklore, 25, out of his habit. His father said: "He takes too much time on these games. You lose out on a social life. He's made contact with people though the game, but it's not the same. I'm a different generation, though. Perhaps I don't understand it."

Second Skin, which made its global premiere this weekend at a festival in Austin, Texas, aims to document the real-life implications of a virtual existence. Documenting stories of chronic addiction as well as of romances that blossomed during shared virtual quests, it is a work of cyber-anthropology that shows the dark and light faces of the phenomenon.

Juan Carlos Piñeiro Escoriaza, the film's director, suggests the importance of virtual worlds has become increasingly apparent. He said: "When you look at online games, you are looking at the future of our society. Over the next five to 10 years, you will start to see real and online life merge, to the point where this virtual landscape is going to be so real it will be difficult to tell the difference."

The negative view of online gaming, in which spotty young men forego all social and sexual interaction in favour of their virtual life, is not a true picture, Escoriaza claimed. His film tells the story of a seriously disabled man who has been looked after by his family all his life. In World Of Warcraft this man is the leader of a guild a massive band of fellow adventurers and holds a power status the exact reverse of his real life.

Online gaming can spark romances between shy people who feel getting to know each other through speaking in games is like falling in love "from the inside out". Their relationships are then tested in situations that would never be found in real life, such as attacks by wolves.

Escoriaza said: "What a lot of these double lives allow is the freedom to be yourself. Whereas in real life, you're tied down by what you look like, who you are, how people perceive you, how you dress. In the game you choose everything. So if you're spending 30 or 40 hours a week inside the game, being this person, what's to say it's not real life?"

One gamer, Andrew Mitchell, 18, from Milton, Glasgow, spends up to 12 hours a day playing World Of Warcraft in an internet cafe that he visits every day after school and all day at weekends. He has three characters a druid, a knight and an elf, all powered up to the fabled "level 70" status, which can take over 30 full days of play, or 720 hours.

He said: "World Of Warcraft can be a better world, because you don't get people threatening each other and you can resurrect yourself when you die. Where I stay is very lonely, because I don't have any friends. That's one of the reasons I play. You're not allowed to make threats to other people in World Of Warcraft."

Psychologists are becoming interested in online gaming. Cynthia McVey, head of the department of psychology at Glasgow Caledonian University, warned that WOW could be addictive because players become addicted to the endorphin rush they get from success.

She said: "If you were in an occupation that was unrewarding or of low status or if you feel you're letting down your friends and family by not fulfilling what you're capable of, you could get some sort of high from playing. But if you found you were very successful as part of a team where you developed a status, gaming could be something that would be difficult to live without."