Behind a display window, plural of reel units are disposed. Each of the reel
units has an outer reel and an inner reel that are coaxially and independently
rotated. The inner reel carries plural inner symbols at a predetermined pitch.
The outer reel carries outer symbols representing conditions of a second rotation
of the inner reel. The plural inner reels stop rotating to complete a symbol combination.
When the symbol combination for losing is completed, the outer reel is rotated
and stopped. Then the second rotation of the inner reel starts rotating, which
carries the inner symbol on which the outer symbol is disposed. In the second rotation,
a rotational direction and a rotational speed is determined in accordance with
a kind of the outer symbol. When the second rotation of the inner reel stops, another
symbol combination is completed on the winning line.
