In terms of collecting treasure, the owners of World of Warcraft, Blizzard Entertainment, do best of all. The world’s most popular online computer game is probably the world’s most profitable title, too — with 8.5 million players paying £8.99 a month ($15 in the US) to maintain their presence in the Tolkienesque lands of Azeroth.

WoW is less than three years old, but it has become a global phenomenon, although for timezone and language reasons, realms are separated by continent. Not everybody may want to spend several hours a week engaged in swords and sorcery, but it adds up.

There are eight different language versions of WoW. In North America, two million people have signed up; there are a further 1.5 million in Europe, battling it out online.

However, it is China where WoW has really taken off. In the officially communist state there are 3.5 million players — paying up in a land where piracy has been a problem for other media companies, and demonstrating that it is possible to create online content that people will pay for.

The result is a boon for Vivendi, the French media conglomerate that, through a dizzying set of acquisitions and divestments, has ended up owning Blizzard, as well as Universal Music — home to Snow Patrol and 50 Cent — French phone companies and a satellite broadcaster. The games business may be small in comparison with Vivendi’s other operations, but it is the fastest growing, doubling profits to 115 million (£78 million) in 2006.

Azeroth, though, cannot afford to stand still. Teething troubles meant that the WoW upgrade, The Burning Crusade, missed the Christmas season, but devotees kept £29.99 aside for the new year, for the chance to become a blood elf or get into “jewelcrafting” — a new activity that has boosted the value of gems discovered online.

In the two months after its launch, The Burning Crusade sold 3.5 million units at a typical price of $39.99, with the China edition yet to come. In the first 24 hours after the game went on sale in January, nearly 2.4 million copies were sold, a record for a PC-based computer game, where sales typically lag behind those of a console game.

A rough estimated gross sales total is around $140 million (about £71 million) — the size of a modestly successful Hollywood movie — and that is before a boost in subscriptions is taken into account. Vivendi predicts that overall turnover in its games business will be around 1 billion in 2007, a 20 per cent increase on the year; and technically WoW would be Europe’s most valuable computer games franchise, except that the game is developed from Blizzard’s headquarters in California.

And the business of WoW does not end there. There is a thriving market in virtual characters, to save a newcomer the bother of rising to level 70, the highest allowed in The Burning Crusade. On a market place such as IGE.com, a male troll hunter — top of the range at level 70 — is available for £383.74; slightly inferior characters can cost £200-£300, part of a growing global market for virtual assets that has been projected to be worth £4.5 billion by 2009. The business is frowned upon and discouraged by Blizzard.

The virtual world is becoming an economic powerhouse in its own right, and WoW is leading the way. Never have gnomes and elves made so much money.