I'm no expert, but it sounds like your son is not in control of his attention - yet. To control his own mind, he needs to learn to control his attention. Right now, he's a teenager with bad mental habits. He can't break those habits without some help.

It seems, he is so accustomed to you taking care of him, he has no reason to focus his attention on anything but a game. Help him adjust his priorities. Stop letting him take you for granted. Ask once, and if he does not answer, assume his answer is no. No reply, no food. Not ready, he gets left behind. He needs you to disrupt his expectations, make him think about what he needs, instead of what he wants.

Be a bit more transactional. You do this, you get that. You do nothing, you get nothing. Real world stuff. Stop being the dad who fixes everything, hands out money and buys stuff and expects nothing in return.

He will resist. He might rebel. he might argue. He might say he hates you. So what? Those are signs he is coming out of his little boy bubble and entering the adult world.

I think you have good instincts and it took you too long, but you finally acted on them. If that made you uncomfortable, imagine your son remaining exactly as he is now 10, 20 or 30 years from now.