It nudged ArenaNet’s free-to-play Guild Wars from third, as DDO went free-to-play itself thanks to the Eberron Unlimited add-on. Runescape 2nd.
Naturally the top spot belongs to industry heavy weight, World of Warcraft. The NPD Group surveyed a random 19,000 in the US and found that 30 percent played WoW, 10 percent enjoyed some Runescape and 7 percent were firing up DDO: Eberron Unlimited.
Micro-transactions are what keep DDO going now, with the game completely free-to-play until you start to push past level 20 and then the full features of the auction house, guilds and support mechanics come at a cost.
Sadly DDO is not using this new model in Europe yet, meaning we still have to shell out a fixed number of clams every month; however we can use the free US servers.
Source: Massively