A computer game program implements a position information obtaining function of obtaining first position information indicating a first position in a game field and second position information indicating a second position in the game field, a position information updating function of respectively updating the first position information and the second position information to move the first position and the second position in response to an operation input by a player, a position identifying function of determining a third position on a first line in accordance with the second position, the first line being a fine that passes through the first position and a predetermined fixed position set in the game field, and a direction determining function of determining a direction in which a predetermined game effect is produced in the game field, in accordance with the first position, the second position, and the third position.