I think it has lot to do with just more folks in the US liking on-line war sims (i.e., cultural of a sort). It's not just propensity for on-line gaming, either -- it's the type of on-line gaming, too. For example, lots of South Koreans play on-line games, but I don't think we have many South Koreans playing AH. There are more US players in WWIIOL, Battlefield 1942, etc.