Don't have kids, just what I went through. I have a gaming addiction from 7, now late 20's. It's incredibly hard to break honestly, even now but I did fine in school and uni, have a career, car and house.

My parents basically itemised the things they want me to do including chores, practice, studies and homework. Can be a daily to do list, a timetable, incremental goals, etc. There are non negotiable events like dinner or holiday celebrations. as long as I do it, they let me game in my free time. They checked and if I don't, then the game goes away or some other disciplinary action (i got caned but that's not acceptable nowdays).

It just taught me how to prioritise my needs and wants so I can maintain my lifestyle.

As for the anger and violence, unfortunately I don't have an answer. My dad always just got angrier and caned me if I got defiant. That's not something you can do nowadays.