Odd but true: one of the world's most successful games is written by people who aren't crazy about video games, and played by more than a million people who aren't really gamers.

According to the mantra, Championship Manager has been written by football fans for football fans, and the secret of its success is that it provides a more comprehensive and more detailed simulation of the game than any of the alternatives. And with 26 leagues from Brazil to Norway, and details of more than 130,000 players, the most comprehensive and most detailed version so far is due to reach the shops tomorrow.

Although Championship Manager 01/02 is being called the 10th anniversary edition, the game goes back to the early 80s. Two teenagers, Paul and Oliver Collyer, wanted a better football management game to play, so they wrote one. They started it in Basic on an Acorn BBC B, and progressed through an Amstrad and an Atari ST to an Amiga. By this time their friends were playing the game too, and they decided to look for a publisher.

This idea was not a success. Publishers were looking for polished graphics and "eye candy", which CM lacked. What it had was text and a lot of player stats, the merits of which did not emerge until you had spent some time playing it. None the less, the game was finally published in 1992, by Domark, which was taken over by the current publisher, Eidos Interactive. After a slow start, word of mouth eventually made Championship Manager an almost permanent fixture in the British games charts, and it is now played all over the world in nine languages.

CM has been completely rewritten three times since. So far, fans have seen two great leaps forward with CM2 and CM3, the current "engine". CM4 is due next October. And what started as a home hobby has become a small company, Sports Interactive, with offices over the top of Hotblack Desiato, the Islington estate agent whose name is known across the galaxy - or at least to lovers of The Hitchhiker's Guide to the Galaxy.

SI is now run by Miles, an ebullient 29-year-old who goes without a surname in interviews and on the company's website (it is Jacobson). Like everyone involved, he's a football fan and a Championship Manager fan. His first involvement was as a play- tester for CM2, then he started an unofficial update for the game data, and then a Championship Manager website. He contributed to the Collyers' efforts - "I started off doing Watford stats," he says - and was soon looking after the whole database, which has 1,500 amateur contributors assessing players for the game. Being more than a little entrepreneurial, he was also involved in the music business through Southern Fried records, and as a compiler of commercial soundtracks for video games such as the Gran Turismo series and N-Gen. The Collyers started to use him as a business consultant, which led to him becoming SI's managing director.

For the Collyers, finding Miles must have been a relief. Oliver (Ov) had found that what started as a schoolboy hobby had somehow consumed his entire adult life, and he wanted a break. He has retired and gone off to Australia ( www.sigames.com/eng/latestnews_sigames_aug01.shtml#ovleave) for a few months. Paul is still "absolutely essential in a programming capacity," says Miles: he is working on the game engine for CM4. However, "he tends to spend most of his time in Sweden, with his girlfriend," working with the Islington team via the net.

Plans for the future of Championship Manager are much the same, and will be driven by feedback from fans. The aim is to make the game even more realistic, not by adding graphics but by providing more stats for more players in more leagues. The 144 stats - not just for footballing skills but for character and temperament - govern how players respond to you, as manager, and how they perform on the pitch. Championship Manager 3 started with a database of 40,000 players, and CM4 is aiming for 10 more leagues and 200,000 players. It is a unique resource. Not only can PC-based gamers find terrific prospects at obscure foreign clubs, so can real agents and scouts.

There is also the idea of making CM4 a network game, where the stats can be updated continuously, instead of once a year, on CD. This will also enable CM play ers to play against other fans in leagues across the globe. The game will also appear on Microsoft's Xbox console, which is possible because it uses PC technology and also includes the hard drive that is essential for saving games. A saved game file can top 100 megabytes, and Miles says he once reached 790MB.

The only black cloud on the horizon is the idea that they might be stopped from using real player names. "In Germany, we can't, and in Germany we don't sell a lot of copies," he says.

Miles wants SI to become "the Man United of video games" with tie-ins and merchandising deals. "We're planning to release over 40 products in the next two years," he says. These include Umbro football shirts, and the use of CM stats in Konami's soccer game, ISS Pro. The next is Championship Manager Quiz (www.sigames.com/eng/softography_cmquiz. shtml), which should be out on the PC and Sony PlayStation for Christmas.

But at the moment, everything is overshadowed by Championship Manager 01/02, which brings the stats up to date. "The best thing about finishing the game is that I'll be able to play it!" Miles exclaims. "I'll probably be able to play about 15seasons with Watford before I have to start testing ChampMan 4. It's a hard life. I've got the worst job in the world, me."

Yeah, right.