I think my son is addicted to gaming.  He is now 30 and I don't know how to talk to him about it. He is very independent but I worry he is closing up

Have you joined the Parent Support forum? You can find it on the forum index page, at the bottom of the "Welcome" section. There you might get ideas and encouragement from others with similar concerns about their own children.

I don't have much insight into your situation, as I'm the one who was a distraction-junkie. I do wonder whether your son has something going on in his life that is pushing him toward gaming, some conflict or other bad situation from which he is trying to escape. If that's it, then an indirect approach might work: don't make it about games, but about his own (other) goals for his life, where he'd like to be in five years or ten, and what other things in his life are making it difficult for him to get there.

I would also say that, at 30, your son should be independent! He's going to make his own mistakes, and there's only so much his mother can do about it. Whether he listens to you, I suppose, depends on the kind of relationship you have with him now.

(I write this as the father of two young people just now entering into adulthood.)