Compared to most single-player video games, online games, especially MMOs, have a much longer life expectancy. The interaction and competition among the community can provide MMO players with sustainable pleasures. Thus, many MMOs remain popular for years, even under today’s competitive game market where new games are popping up daily.

However, players always go bored after repeating the same thing for some time, even for the most successful MMO. So it is conventional for developers to add new content regularly, so as to prevent their players from burning out. Conquer Online, the most successful Chinese style MMO, is a good example. Released in 2003, this free MMO has renowned success with 7 language versions and millions of players in the worldwide mark