Industry-research firm DFC Intelligence reports that the worldwide online market will effectively quadruple in the next five years,going from ?3.4 billion last year to more than ?13 billion in 2011.

DFC expects online gaming subscriptions to account for ?6.8 billion worldwide, digital distribution to equal ?5.4 billion, and advertising revenue to add up to ?1 billion."Digital distribution and virtual item sales have started to do very well in certain Asian markets and these distribution models are expected to start having increased success on an international basis," DFC analyst Alexis Madrigal said in a statement.

DFC also issued out some problems that block the growth of MMO.One of them is the lack of crossover international success for games. What works in the Korean market may not do as well as in China,Japan or the US.