Unlike games in the Americas, Asian MMOs are rarely in the monthly subscription format that we know and (perhaps) love -- instead, most games are free (no box) with fees based on time spent in the game or microtransactions of some sort. (The box model is hard to push in Asia because people want to try before they buy -- though we'd be perfectly happy to try out MMOs without shelling out $50 for a game box.) The big question is, for both Asian and American game developers, is what motivates people to pay for a service? Is it a particular super-cool item? Is it money in exchange for time that would be spent grinding or leveling? Because MMOs are never-ending projects requiring ongoing development and maintenance resources, knowing what your potential players are willing to give you money for is crucial -- and it's distinctly different between an Asian and an American audience.
American companies trying to break into the lucrative Asian market tend to hit a brick wall by means of these, and other, cultural differences. The same types of gameplay that Americans love may be found offensive to another culture. (For example, to appease Chinese censors, World of Warcraft's undead character models were changed in the Chinese client. Chinese players won't see any protruding bones.) And worse than that, a game that's successful in Vietnam could be a complete flop in Thailand -- though all of Asia is an MMO hotbed, each country's cultural norms are different. For a want-to-be MMO-maker, this means localizing your game requires a great deal of attention.
Though everyone seems to laud globalization, some games simply aren't suited for an international market. Of the popular western MMOs, World of Warcraft is the only one to have broken into the Asian market, with the help of distributor The9, who handles all of the game's Chinese operations. But for this one success story, many games have failed. For example, Habbo Hotel's Sulka Haro, when asked why Habbo wasn't being rolled out in China, responded simply, "There is no China." For many American companies looking for a piece of the Asian gaming market, it's just that simple.