There is provided a game system which can change the configuration of an image based on the detected illuminating position of a light illuminating device to improve the effect of a game. The game system includes a light detection section which detects a position of a spotlight on a screen formed by an infrared light emitting section, an area setting section which sets a given specified area based on the position of the spotlight detected by the position detection section, and an image effect section which displays an image so that the specified area is displayed in a manner different from that of an area other than the specified area.