The MMO market is dominated by World of Warcraft, which has over 60% market share as measured by number of subscriptions. WoW surpassed 10 million subscribers on January 22, 2008, with 2.5 million subscribers in North America, 2 million in Europe, and 5.5 million in Asia.

World of Warcraft is followed by RuneScape, Lineage, and Lineage II (7.5%, 6.6%, and 6.3% market share, respectively). The top 10 MMOGs control 93.2% of subscribers.

Fantasy MMOGs are the most popular genre, with 94.2% market share.

MMOGChart.com has done a great job of compiling information on the industry.