Disclosed are an online game providing method including the steps of: maintaining a unit information database recording unit information on at least one unit, in which the unit information includes at least one piece of unit ability information and sync point information; maintaining a pilot information database recording pilot information on at least one pilot, in which the pilot information includes a unit identifier associated with a pilot, at least one piece of pilot ability information and unit ability information associated with the pilot ability information; receiving updating request information on first pilot ability information of a first pilot; searching for unit identifier information associated with the first pilot by referring to the pilot information database; searching for sync point information associated with the searched unit identifier information by referring to the unit information database; and updating and recording first pilot ability information and unit ability information associated therewith in accordance with the searched sync point information, respectively, and a system thereof.