Developer create code for (FPS) Socket or almost all project by creating following :
1: server side
2: client side
server side : is a logic of functions and the backend code something like ( c# , java , c++ , ... ) at this section anything user send to the (channel of socket or api request) the server class methods
will check it then will send provide response based on the input client send in request.
client side : is a graphicly side with smaller thing of logics to determined a role for each users ( if client banned display somethin else let him join game) but at this section there is nothing logic happen with database directly 99.9%
the programmers specially hackers (hck the client side) by change the input while it sending to the server side based on some security issues by doing following :
1: searching for the input in memory and get the really address (offsets) with (size of this address) then Convery it from byte to hex .
2: access this offsets and change the value then send the request to server.
3: good logic code writer will detect if the request is forbidding for that user ( then band him/her)
the above help to change the your speed , ammo , not death , high jump , (aim at game not the mouse dropping) ,but it was higher risk
there is some thing different with Aim , ESP .
Not professional but I hope to learning more but i say what i know