1. A system for controlling a massively multiplayer online role-playing game (MMORPG), the system comprising: a user-interface (UI) selection unit configured to allow a user to select a UI in the user's device; an action log unit configured to record logs of the user's actions input through the UI, the actions being associated with status information of the user's character and opponent characters; a pattern detector unit configured to extract correlation rules for the status information and the associated actions recorded in the logs; and an artificial intelligence (AI) player unit configured to control a substitute player for the user based on the correlation rules, such that the substitute player automatically reproduces actions of the user.