China has as pretty scary high success rate with policies often deemed "doomed to fail" by the outside world.

I wouldn't be surprised in the slightest if it's highly successful at cutting down on game addiction (which is a problem you easily carry into adulthood).

Worth mentioning they aren't banning children playing games outside these hours. They are only restricting access to online games. Namely multiplayer games like Honor of Kings. If a parent is happy for their child to play other games that don't require online services they are free to do that.