Objectively, you don't know this decision is bad yet.
https://en.wikipedia.org/wiki/List_of_banned_video_games_in_...
If it exhibits short term negative effects, it'd be obvious what to do.
In addition to video games we also censor television, books, porn, the internet and music. Slippery, slippery slope... it's now illegal for doctors to talk about the facilities and treatment they observe working with attempted-illegal immigrants detained indefinitely by the AU government.
How can it be good? There's a million ways it can be good, but you and I wouldn't know them for sure. Just like how arbitrary Western policies can swing either the positive or negative side of consequences. Just like how a large portion of Britain thinks Brexit is good, and a large portion thinks it's bad. You can't just assume your viewpoint is automatically assumed to correct. You have just as much responsibility to defend your position as the opposition does to have to defend it against your inquisitions.
Before you judge, you're viewing China from a lens of systematic Western propaganda. You automatically assume their crazy laws are crazier than those proposed in the US, like New York's anti-large-soda law, which is also an example of mass behavior control.
From China's perspective, they probably think America is barbaric in terms of gun control (guns are generally not allowed in China), just as we from our perspective think it's barbaric they censor their internet.
But the government couldn't censor their views, because it would be against our constitutional rights. For better or for worse, we think the freedom of expression outweigh the benefit of having a government ban expressions.
I am glad that doesn't happen here in the Western world, but it's a good idea to try to think from their point of views of how censorship might be good.