Market analyst Screen Digest has reported a mixed bag for the subscription-based MMO industry.
Total market worth in Europe and North America rose from $1.4 billion in 2008 to $1.6 billion last year, its latest MMOG Report found.
It predicted this would rise to $2 billion by 2014, despite the rise of free to play games.
However, average revenue per user had declined by 10 per cent over the year, Screen Digest claimed.
Blizzard's position as industry leader - with World of Warcraft - appeared unassailable, but its share of the subscription MMO market had declined from 60 per cent to 54 per cent between 2008 and 2009.
The report did not cover the Asian market, but found that 56 per cent of subscriptions in the Western territories covered hailed from North America.
Screen Digest estimated that Western subscriptions reached 13 million in total by the end of last year.