Worldwide online game subscription revenue grew 43 percent to $2 billion in 2005, according to a video gaming market research firm.
Online subscriptions remain a fraction of the estimated $29 billion in overall video game sales in 2005, but San Diego, Calif.-based DFC Intelligence expects the segment will reach $6.8 billion in sales by 2011.
"It's on the cusp of strong growth and becoming a mainstream part of gaming," said DFC's president David Cole.
So-called massively multiplayer online games, such as "World of Warcraft," accounted for more than half of the subscription sales in 2005 while one-fifth came from casual games. The remainder was split among sports, strategy, first-person shooter and children's games.
Today, the vast majority of subscriptions are generated from games played on PCs, but in five years, DFC forecasts that console-based online games will become a bigger driver, accounting for 29 percent of worldwide online subscription revenue.