How Do Those Android "Modding/Hacking" Apps Work?

Like you know those android apps for rooted android devices, where you enter a value and it changes the value of something ingame?

i.e. "Enter Value: 99999999"

Gold is now set to 99999999

Its not that I'm trying to mod any games/apps, I'm just curious as to how they work. Do they just change the XML values within an app's files? or does it send some type of request to the app server?

Thanks

(btw, I know this isn't really hacking related...at least I don't think, sorry about that)