Warhammer 40,000 - set in a science fantasy universe - has just turned 25. Why are grown men still launching tabletop war?

You may have walked past one of the hundreds of Games Workshops on the High Street. You may even have wandered in, especially if you are a teenage boy or the parent of one.

If you know your Necrons (virtually invincible soulless metal warriors) from your Dark Eldar (sadistic elfin pirates), the chances are you are one of the dedicated tribe who have signed up to what fans call The Hobby.

Most days of the week, on table tops in "hobby centre" shops, in office lunchrooms, and bedrooms, players gather around home-constructed battle fields with miniature ruins and petrified forests. They assemble and paint small model fighters from a chosen army (several to collect) and using dice, tape measures and special rule books, battle rival militia in a fictional science fiction universe set in the 41st Millennium, called Warhammer 40,000.

Launched 25 years ago, 40K was so named to distinguish it from traditional fantasy Warhammer of elves and vampires. Both lines, together with a Lord of the Rings brand, continue to attract hundreds of thousands of new fans in Britain and across the world - 70% of sales are abroad.

Image caption Dark Eldar on left (photos by Jordan Louis); Necrons on right (photos by AdmGR and Victor Yoon)

The appeal is in collecting, assembling and painting the models, for play, which are manufactured in Nottingham (and Memphis, Tennessee) and sold through the Games Workshops chain and by mail order. Blood, torn flesh, grimacing skulls and very large guns and tanks feature prominently in the detailed artwork.

Despite the competition from online or console-based gaming, Warhammer continues to thrive, with successful spin-off novels set in the 40K universe. How many other British companies, for example, could report a 40% rise in their latest half-year pre-tax profits?

Image caption A tournament at the company's castle-themed HQ

"It's like why theatre remains popular in the age of cinema," says 32-year-old Andrew Ruddick from Cambridge, explaining its enduring appeal. He describes himself as a "relapsed" Warhammer gamer, slipping back into it in his 20s with friends. "There's an intimacy. With tabletop gaming you are there."

Several hundred such gamers gather regularly at Games Workshop's Hall of Fame, next to its Nottingham factory, for tournaments. Most, but certainly not all, are male.

They play on teams with names like Alfa Geek, Purple Pain and I See Lead People. Heavy rule books or codices (all published by GW) are consulted intently. Templates and tape measures are used to confirm terrain advanced and numbers of casualties. Occasionally a whoop of victory goes up from a table.

Kathryn Turner, 13, is playing a doubles match with her father Stephen against two strapping 30-something blokes. The poker-face calm with which she deploys her Tyranids (world-devouring aliens) is impressive.

You need at least £200 just to set up a half-decent legal army Craig Lowdon

"It's fun and I like spending this time with my dad," she says. Her mother Sue is one of the crop of self-confessed Warhammer Widows who spend all day in the cafe. Kathryn admits to sometimes wearing pink on the first day to psych out the male opponents. "I'm moving on to play with Sisters of Battle next," she says - it's an army of fanatical warrior nuns with flamethrowers.

The whole aesthetic is, as Andrew Ruddick puts it "very masculine". But the appeal is its epic scale, says Warhammer fan and Marvel X-Men comic writer, Kieron Gillen. "It's a hilariously OTT maximalist universe at an operatic pitch. There are some people who think less is more. Warhammer, conversely, believes that more is always more."

Foot-high model Titans can be brought out for particular battles. "Warhammer gone nuts," as my 12-year-old son puts it.

Image caption Figurines are painted by hand

Gillen contrasts Warhammer 40K to role-playing fantasy gaming like the online World of Warcraft (the modern equivalent of Dungeons and Dragons). "In Warcraft it's made so there are no bad guys. In Warhammer there are no good guys. They're all bad. It's a universe that's simultaneously nihilistic and joyous. It's incredibly British in that way."

Gary Chalk, a 59-year-old fantasy game creator and illustrator, knows all about its Britishness. He used to design Warhammer and Warhammer 40K games in the 1980s and 90s. His trademark wit is evident in Bloodbath at Orc's Drift (an elvish version of the Michael Caine film Zulu) and a naval ship battle he called "All the Dwarves Love a Sailor". Still an enthusiastic table-top gamer, he does, however, believe Games Workshop uses its monopoly on the products to target and exploit increasingly younger fans. The prices for essential models, paints and books are "eyewatering", he says.

"They are not selling a hobby. They are selling a craze."

Several players say they feel exploited. "You need at least £200 just to set up a half-decent legal army for a game, and if you want a board and scenery to go to play with friends you're looking at least £200 on top of that," says Craig Lowdon, 25, of Crewe.

Games Workshop's executives say they don't do media interviews, preferring to focus on their hobbyists. But chief executive officer Mark Wells emails me about the claim of price exploitation. "That would go against everything we stand for. It's just not in our nature," he writes.

Image caption Women and girls do play, but are outnumbered

And Chalk claims the game is now less interesting. "The original rules were about fantasy combat and creating character. Now the rules only work within their imaginary world, with their figures and it cuts out all the other influences."

But its legion of fans, including older fans, see a timeless appeal.

"[There's] the satisfaction of looking at ranks of badly-daubed Skaven (man-sized anthropomorphic rats) and knowing they're yours and you made them in a real way," says Kieron Gillen.

"It's absolutely the part of the brain that made other generations make model trains."