A device for electrical isolation is suitable for installation in the core hole of a toroidal core. When S\u2032 >Smax\xd7A is satisfied, it is determined that the signal intensity S at the particular pixel=Save\xd7C, whereas when S\u2032 <Smin\xd7B is satisfied, it is determined that the signal intensity S =Save\xd7D, and processing is performed so as to obtain an appropriate intensity S. When the marker lands upon a previously marked position, the game ends. After the vehicle engine has stopped, communication of messages may continue on an intermittent basis, or may be suspended after a predetermined time has elapsed or when the vehicle battery voltage reaches a predetermined threshold. One or more of the wager areas are selectable by the player for wagering.