Methods, systems, and computer programs for generating revenue in an online game are presented. One method includes an operation for creating, in the online game, a first virtual currency and a game
score, where the amount of the first virtual currency can be increased in exchange for real currency. The first virtual currency can be traded for advancement in the online game. Further, a game module, that is an autonomous game within the online game, is started, and a second virtual currency and a module
score are created in the game module. The amount of the second virtual currency can be increased in exchange for real currency, where the second virtual currency can be traded for advancement in the game module and cannot be traded for advancement in the online game outside of the game module. Advancement in the game module increases the module
score and does not increase the game score. In addition, at least one form of advancement in the game module can be obtained with the second virtual currency and cannot be obtained with the first virtual currency.