The server apparatus is applied to a game system which has a storage unit storing gaming dynamic images different from each other in association with a stream ID for identifying each gaming dynamic image. The game system acquires a playing dynamic image photographed by a portable phone and a stream ID of the playing dynamic image via a network. Base on the acquisition result, the game system determines the gaming dynamic image whose stream ID corresponds to the stream ID of the playing dynamic image acquired as a target gaming dynamic image, and provides a dynamic-image delivery service so that a delivery screen is displayed at each personal computer, the delivery screen including a composite dynamic image where the playing dynamic image and the target gaming dynamic image are synthesized.