I'm not a violent man. My physical aggression is limited to kicking non-existent objects when my train gets cancelled, or slamming the phone down on British Gas when they cold-call for the third time in a week. But in the past fortnight, I've been on a sustained campaign of slaughter – several dozen boars, umpteen Dustwind Harpies and Razormane Dustrunners, a vicious troll called Zalazane – and that's just for starters. What's more, dispatching these computer-generated characters to the hereafter was utterly absorbing, and if I hadn't been ordered to stop "researching" and start writing, I'd probably have carried on vanquishing evil while my phone rang out and takeaway cartons piled up on my desk.

That, I'm ashamed to admit, is the power of World of Warcraft. Slaying baddies is a major theme running through the bestselling games, and World of Warcraft – or WoW – is no exception. Its status as by far the most popular MMORPG (massively multiplayer online role-playing game) makes it an appealing prospect for gamers, as it offers the ability to collude with – or massacre – 11 million other players across the internet. An awesome bloodbath, and a colossal source of revenue. Aside from the cost of the game, there's a monthly subscription fee of between £7 and £10. That works out at a pretty hefty annual bill for a player to run amok with a Dragonbone Greatsword, but there's a good reason for millions of people coughing up for WoW: it's fantastically – or worryingly – addictive.

The devotion that war games inspire – particularly the MMORPG variety – is well documented; when the new expansion pack for WoW was launched last week, queues were forming in London's Oxford Street hours beforehand, and the person at the front was so overwhelmed when the barriers were lifted that he passed out. But Jon Appleyard, a WoW player who spends up to three nights a week playing alongside other members of his WoW guild, Second Blood, is sanguine about the role the game plays in his life. "I'll admit I use it as a comfort thing," he says, "a dependable way of escaping from everyday life. If I wasn't playing WoW, I'd probably be getting wasted down the pub."

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But for those who have "addictive personalities", playing WoW is not so benign an activity. There are plenty of stories of gaming leading to relationship breakdowns. Wendy Kays, author of Game Widow, watched her marriage flounder as a result of her husband's addiction to online war gaming. "It was bizarre," she says. "There were all the signs of drug addiction – but no drugs." And there are many instances of online rivalries leading to real altercations. "There are rumours of real-life murders," says Appleyard, "and I think they're probably true. There was one guy who lent someone a Sword of Slaying or something in the game EverQuest. He never got it back, so he tracked the guy down and killed him."

But what is it about these games that inspires such powerful emotions? As someone whose interest in gaming is limited to occasionally shoving coins into fruit machines, I was curious to try WoW. After creating my character, an apprentice mage (whom I wanted to call Geoff, or Mike, but ended up naming Kohntarkosz to avoid being laughed at by a Paladin or a Night Elf), I set a trepidatious foot into the Valley of Trials.

Immediately, some orcs asked me to execute a few harmless creatures using a gnarled stick, for which I was rewarded with some coins, or a shabby piece of clothing. Bewildered by my surroundings, I carried on doing what I was told – only obeying orders, if you like – and pretty soon I'd gained the ability to cast a fireball spell, freeze enemies to the spot and turn humans into sheep. These skills might be worth little at Tesco, but in the wastes of Durotar they were boons. I was sent on killing sprees in the Echo Isles; I rode a winged creature to the Horde stronghold of Orgrimmar to receive orders from Thrall, I maimed dozens while searching for the secret of the Samophlange. And, to my horror, I found myself utterly bewitched by the game.

What's most astonishing is its depth and complexity; even seasoned players such as Appleyard admit that they feel they're barely scraping the surface. And it's designed in such a way that even first-timers, or "noobs", are drip-fed just enough to keep them coming back for more: the prospect of increasing a level, or gaining possession of a fetching cape, or being praised and sent on new, exciting missions.

While war games have long captured our imaginations, Wendy Kays believes that blaming the violent aspect of WoW and the like for their addictive properties is a red herring; she believes it's down to that sense of achievement the games bestow on players. "Despite the fact that you're in combat for a lot of the time, the point of WoW isn't killing. It's just a safe way to explore new things, an inexpensive way to feel as if you're being a pioneer. It's emotionally compelling – and I have to say that while researching the game I ended up loving it."

It's a strange admission from someone whose book tells of the dangers of online gaming, and the steps she and her husband made to get their relationship back on track. "I'm not crusading against them, and it would be easy for me to appear joyless. No, I think they're a wonderful gift that has the capacity to be badly misused."

In two weeks as a subscriber to WoW, I played it for some 27 hours – a shocking statistic. How could that time have been better spent? That leads to questions surrounding the point of our existence: is learning to knit or going to the cinema any more use than emerging triumphant from Ragefire Chasm having vanquished Jergosh the Invoker? "That's the question gamers need to address," says Kays. "If people have thought about this, and decide to choose gaming, that's fine – they should go ahead and have a great time. But the ones who haven't – and particularly if they have responsibility for children – just need to be asked the question, otherwise in five years they'll wonder where all that time went."

Fortunately, this isn't a question I will confront. My frustration at forgetting to pick up a Flawed Power Stone en route to the Altar of Fire in Dreadmist Den meant that I couldn't be arsed to return to Ak'Zeloth to get one. So I've just logged out – and I've moved the game to the trash. I've been wowed by WoW, but when real life starts to feel grim, I don't want to have to slaughter a bunch of Voidwalker Minions to make me feel better.

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Sure-fire hits: The best war games

Call of Duty: World at War

Publisher: Activision (£49.99) Platform: PC, Nintendo, PlayStation, Xbox 360

Scenario: Second World War in the Pacific and Europe

Popularity: 'Call of Duty 4: Modern Warfare' was last year's world's best-selling game

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Gears of War 2

Publisher: Microsoft Game Studios (£44.99)

Platform: Xbox 360

Scenario: The Delta Squad fight the Locust Horde on Sera

Popularity: 15 million gameplay hours racked up during opening weekend

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World of Warcraft: Wrath of the Lich King

Publisher: Vivendi (£34.98, plus £8.99/month subscription)

Platform: PC, Mac

Scenario: The Horde battle the Alliance in the world of Azeroth

Popularity: More than 11 million active 'WoW' players

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Fallout 3

Publisher: Bethesda (£49.99)

Platform: PC, PlayStation, Xbox

Scenario: Post-apocalyptic United States in the year 2277

Popularity: 4.7 million units shifted in week of release

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Battlefield: Bad Company

Publisher: Electronic Arts (£49.99)

Platform: PlayStation, Xbox

Scenario: War between the US and the Russian Federation

Popularity: The 'Battlefield' franchise has accounted for more than 45,000 years of online gameplay

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