on the field by for example causing the unit to pick them up the game media items or the like that the user obtains in the group battle may be usable not only in a group battle but also in a regular battle next a game system including a server device according to an embodiment of the present invention is described as illustrated in fig1 a game system 10 includes a server device 11 and a plurality of terminal devices 12 the server device 11 and the terminal devices 12 can communicate with each other over a network 13 the server device 11 includes a server communication module 14 a memory module 15 a unit type information retrieval module 16 a deck information retrieval module 17 a unit parameter determination module 18 a unit deployment module 19 a unit parameter variation module 20 and a server control module 21 the server communication module 14 exchanges information with the terminal devices 12 the memory module 15 stores user information 22 the user information 22 is information unique to a user and includes a variety of information used for progress of the game for example as illustrated in fig2 the user information.