1. A data storage medium having stored therein a game program causing a computer of a game machine, including a display screen for displaying a game image and a touch panel covering the display screen, to perform the steps comprising: a display control step of displaying, on the display screen, a game image, including a game character image and a plurality of target images indicative of targets to be specified by a player; a movement control step of moving the target images so that at least one of the plurality of target images passes over the game character image; an input coordinate detecting step of detecting, when the player provides an input onto the touch panel, input coordinates indicative of a position of the input on the display screen; a specified coordinate determining step of determining, when display coordinates of any one of the plurality of target images, at the time of the input provided from the player onto the touch panel, and the input coordinates are within a predetermined range, that the target image has been specified by the player, and determining, based on at least one of a position represented by the display coordinates and a position represented by the input coordinates, specified coordinates indicative of a position specified by the player; and a parameter updating step of varying a characteristic parameter, indicative of a characteristic of a game character represented by the game character image, based on a positional relation between the specified coordinates and the game character image.