A rule (applied to a battle) is set according to a stage of the progress of a game every time the stage of the game advances. When a battle is started, either a player character or an enemy character that can execute an action is determined. When it is decided that the player character can execute the action, a player selects the action of the player character. When the action selected by the player is against a rule, a rule violation is recorded. When the result of the action of the player character is also against a rule, a rule violation is recorded. When the rule violation is recorded, a predetermined penalty is imposed on the player after the battle ends.