Input devices having different key structures are provided so as to selectively connect with a game apparatus. The game apparatus has means for discriminating a kind of the connected input device and storing its result, a memory for storing a key navigation table that sets keys to be operated with respect to action message delivered from a server, corresponding to kinds of the input devices, message display means for displaying the action message delivered from the server, and display means for displaying the key to be operated by the player corresponding to the discriminated input device as a guide icon by referring to the key navigation table when the action message is delivered.