A game system is composed by connecting a game apparatus with a monitor and a percussion type controller. A game player beats a first beating operation surface or a second beating operation surface to input an operation signal from the controller to the game apparatus. In the game apparatus, in response to the operation signal, a player character in a virtual world displayed on the monitor is moved in a left or a right direction. Furthermore, when a sound input by clapping, and so on in the vicinity of a microphone of the controller is present, the game apparatus generates a shock wave from a position of the player character. By the shock wave, a predetermined change such as returning an enemy character to its initial position, gathering fairies in a form of block, and so forth occurs.