Both of my sons went through a phase of playing long hours of sometimes violent video games. We didn’t forbid them, since we knew they’d always be able to go to a friend’s house or secretly do it on their phones. Except that a couple of ultra-violent ones, like Grand Theft Auto, I said “no” to. But we didn’t relent on other requirements like doing homework on time, doing chores, keeping rooms and themselves at least relatively clean, getting good grades, not getting in trouble, no drugs or alcohol, being polite, etc. And they weren’t hanging out with questionable friends, or otherwise getting in any trouble. I believed that video games, even violent ones, were now just a part of our society and we're not going to go away. My kids would just have to figure out how to manage their other responsibilities alongside and hopefully be able to realize the difference between fantasy and reality. And of course, we did our best to instill good values and set good examples.
It worked. After an initial period of obsession, they got bored with them, the video games became an occasional activity, and eventually, they died out altogether in favor of sports and other social activities. Now and then, they’ll play a video game, but it’s rare.