To enhance the game potentialities while eliminating the management by the exclusive servers in the network work games.

A memory management means 2 can delete the module stored in a memory means 1 from the memory means 1 while enabling the replacement of the module by loading the memory means 1 with another module. The memory management means 2 enters the server mode by loading the memory means 1 with a server mode play module based on the input contents in an input means 110 to turn an arbitrary network game machine to the game server. In the server mode, an event management means 4 can set the events based on the contents of the input contents by the players during the server mode play thereby enhancing the enjoyment of the games.