(Sorry, no idea about FIFA, but...) Study up on game ROM hacking (i.e.: SNES, PSX, whatever if need be) What you are ideally looking for when doing this sort of thing is called a "game trainer", AKA Game Shark for PC :-) Hex editor on steroids, basically. There's a piece of software called Bit Slicer for OS X -- https://github.com/zorgiepoo/Bit-Slicer -- that works well for real-time game hacking. Not sure about other platforms, but I'm sure you can find one fairly easily! Good luck.