A storage module is provided for storing game information that is necessary for the progress of the game. A request to allow the game to proceed is acquired from each of a plurality of players, game information is changed according to these requests and stored in the storage module, log information indicating the relation between before and after the game information is changed is stored in the storage means, the log information is used to reproduce game information older than a first point in time until the game information at the first point in time, and the reproduced game information is used to reproduce the progress of the game and provide it to a player.