In a system comprising the disclosed server and a plurality of player terminals, it is possible to suitably and easily alter the accessories and character class of player characters. The server has: a memory means that stores player character data of a plurality of player terminals; a means that confers data indicating the fact that a player character indicated in a party formation command has been added to the same party when a party formation command has been input from a player terminal; a means that acquires changes regarding the accessories or player class of the player character in each player terminal, and updates the character data stored in memory; a means that extracts the other players that form the same party as the player character for which changes have been output; and a means for transmitting said changes to the terminals of the other players that were extracted.