US Patent 7922574 Slot machine and playing method thereof

When the number of bets is determined and a game is started, reels start spinning. After a lapse of a predetermined time, fifteen symbols are repositioned in symbol display regions. By dragging and dropping a repositioned symbol to a crater of a volcano, a performance character, an animation effect to represent a volcanic eruption of the volcano and a sound effect corresponding to a volcanic eruption sound of the volcano are outputted. In case the symbol is dragged and dropped to the outside of a display, a warning sign is indicated as well as a warning sound is outputted.