Score verification system and score verification method of online game

A score verification method for preventing alteration of a score in an online game, comprising:

• reading, by an online game server that manages the online game, a game program of the online game from a game program storage part that stores the game program with identification information attached thereto for identifying the game program and transmitting the game program to a player terminal for playing the online game;
• executing, by the player terminal, the game program and recording an operation history of operation commands of the player;
• calculating, by the player terminal, a first score based upon an operation of the player with respect to the game program;
• transmitting, by the player terminal, information relating to a game result including at least the identification information for identifying the game program, the first score and the operation history to the online game server;
• receiving, by the online game server, information relating to the game result including at least the identification information, the first score and the operation history from the player terminal;
• reading, by the online game server, the game program corresponding to the identification information from the game program storage part, executing the operation commands in accordance with the operation history to reproduce the operation of the player, and calculating a second score based upon the reproduced operation of the player;
• and
• comparing, by the online game server, the first score with the second score to verify whether the first score is a true score,
• wherein the game program includes recording, 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 operation commands are executed, by the online game server, based upon the frame and the elapsed time recorded in the operation history.