When usage command information is received from any one of player terminals, an integrated attack determiner determines whether or not an attack action by an attack command is to be an integrated attack action, in which the attack actions by the attack commands included in a usage history are integrated, on the basis of a current position of the user terminal. The integrated attack determiner also determines attack power specification information capable of specifying the attack power in the case where it is determined that the attack action is to be the integrated attack action. An attack instruction information transmitter transmits attack instruction information indicating a determination result of the integrated attack determiner to the player terminal. A usage history information updater updates the usage history information by adding the received usage command information to the usage history of the attack commands.