how do i make the game client too old?

[qet123]

title please help me fast?
Example : when you login a pop up say the game client too old..
how i can make it ?

[MentaL]

[WickedsInferno]

You should give more info on want you want to know

[qet123]

You should give more info on want you want to know

Let's say i made a new system.mrs and let's say i change zitem.xml but i don't want to let the players enter from the first system.mrs i wanna enter only from the system.mrs and if they enter from the old when you login to the server(connect) a pop up should say the game client too old