More than 8 million subscribers have fallen for World of Warcraft
Demand for subscription massive multiplayer online games (MMOG) will top $2bn (£1.3bn) by 2013, according to a new report.
The study, by analysts Screen Digest, said the market had been driven by attempts to emulate World of Warcraft.
The findings suggest that the MMOG's market in Europe and North America grew by 22% and was worth $1.4bn (£0.9bn).
There are at least 220 active MMOGs, although many of these are exclusive to South East Asia.
Speaking to the BBC, Piers Harding-Rolls - senior analyst with Screen Digest - said that despite the recession, subscription MMOG's were still showing significant growth.
"Some games are eroding World of Warcraft's (WoW) position - Warhammer Online and Age of Conan being the two most significant - but that's more down to their growth rather than any decline on WoW's part.
"WoW's market share was 60% in 2007 and 58% in 2008, but in terms of revenue, it went up year-on-year and is still going big guns.
Mr Harding-Rolls said that a combination of new title releases, different payment systems, and games that target specific demographics had helped the rise in popularity of MMOGs.
10 MOST POPULAR SUBSCRIPTION GAMES IN TERMS OF SPENDING
1) World of Warcraft
2) Club Penguin
4) Eve Online
5) Final Fantasy XI
6) The Lord of the Rings Online
8) Age of Conan
9) City of Heroes
10) EverQuest II
Source: Screen Digest
"If you look at the example of RuneScape, this is a game pitched at a teenage audience. You can play it for free or you can pay a premium and get a better service without advertising.
"It's an effective way to build a subscription base, rather than the traditional routes that involve PR, hype and having a service that has to be almost perfect from day one," he said.
The report examines revenue made from subscription based services, rather than total player numbers, in Europe and North America.
Some games - such as the German title Panfu and Tribal Wars - are in the 10 most popular games when it comes to player numbers, but not in terms of spending.
In addition, some games - such as Warhammer Online - were released late in 2008 and so didn't make the list. However, Mr Harding-Rolls thought that Warhammer would be one of the top three when next years list comes out.
There has been much speculation on how the video games industry would fare during the recession, with many experts - such as the British veteran game designer, Peter Molyneux - expecting a lot of price pressure on games.
Mr Harding-Rolls said that, for now, it was a case of wait and see when it came to MMOGs.
"Under the current conditions, it will probably be harder for publishers to pick up new customers and gamers who have multiple accounts on different games may well scale back which game they play.
"That said, playing a video game - especially a MMOG - is a low value proposition to a user and once you're a subscriber you're likely to stay a subscriber for at least a few months."