1. A method for controlling a computer including a storage unit, the computer providing a game in which a user and an opponent battle against each other, the method comprising the steps of: (a) storing in the storage unit a character table for a plurality of game characters, the character table including an identifier, a health point, an offensive power and one of a plurality of attributes for each of the game characters, wherein the attributes have a superiority inferiority relationship relative to each other; (b) receiving an user input for selecting one or more game characters used by the user for playing a battle event in the game; (c) for a first game character included in the one or more game characters, determining a first number which is the number of game characters that are used by the first user and have the same attribute as the first game character; (d) determining a second number which is the number of game characters that are used by the opponent in the battle event and have an attribute inferior to said same attribute; (e) adjusting the offensive power of the first game character to a larger value as the first and second numbers increase; (f) storing the adjusted offensive power in the storage unit so as to be associated with the identifier of the first game character, thereby updating the character table; (g) displaying a battle screen including a button for accepting an attack execution instruction from the user; and (h) reducing health points of the user and the opponent in accordance with offensive powers of the one or more game characters obtained from the updated character table, while continuously monitoring progress of the battle event.