Abstract: A control method of a game server as a game system includes: a posting acceptance processing step of accepting posting of a game module from a game creator's terminal connected via the Internet; a conversion processing step of converting the game module into a predetermined format in accordance with which the game module is operable in a predetermined virtual machine; a behavior information acquisition processing step of activating the already converted game module by an operation instruction from the game creator's terminal, and acquiring behavior information of the game module under a testing virtual machine module provided with a function of the virtual machine; and a posting registration processing step of storing the already converted game module into game storage means in a case where the acquired behavior information satisfies a predetermined condition, wherein all of the processing steps are performed by being executed by a computer.