a game program storer that stores a game program of the online game with identification information attached thereto for identifying the game program;

a game transmitter that transmits the game program to a player terminal for playing the online game;

a game result receiver that receives information relating to a game result from the player terminal, the information including at least the identification information for identifying the game program, a first score calculated based upon an operation of the game program by the player, and an operation history of operation commands of the player;

a score calculator that reads the game program corresponding to the identification information from the game program storer and executes the operation commands based on the operation history to reproduce the operation of the game program by the player to calculate a second score; and

a score verifier that compares the first score with the second score to verify whether the first score is a true score,

wherein the game program records, in the operation history and at a time of receiving each operation command of the player, a frame and a time elapsed from when the frame was displayed by the game program, the frame and the time elapsed being recorded in association with each received operation command of the player, and

wherein the score calculator reproduces the operation of the game program by the player based upon the frame and the elapsed time recorded in the operation history.