Just to make sure that I have this straight: The parent didn’t know how to successfully influence this individual, you also don’t know how to influence this ind

Just to make sure that I have this straight: The parent didn’t know how to successfully influence this individual, you also don’t know how to influence this individual, so you’re appealing to strangers on the internet for advice about how to forcibly change an adult’s behavior? I doubt you’re going to find any truly applicable advice about forcing this person to behave the way you want them to here. You’re talking about an individual human adult, not some theoretical cookie cutter “18 year old.” > The parent has tried locking the computer in a different room… This is the strategy that I use to keep my cat from eating all of his treats. I have never considered treating a human adult in such an infantilizing way. Considering the fact that you’re playing a game of internet telephone to figure out how to modify behavior that you don’t like, I’d suggest helping this adult get away from his or her parents. Or at the very least, ask yourself why you are fixated on this particular behavior and why you feel entitled to eliminate it. You didn’t ask “How can I help make this person happier or more successful?” or “How can I improve communication with this person?”, you asked “How do I stamp out this behavior that my relative finds distasteful?” If your family member boils their relationship problem with their child down to a single negative behavior, it’s likely that there is a mutual disdain that’s much, MUCH worse than gaming. If the parent isn’t interested in addressing underlying issues, then the solution is to help that adult to move out!