Don't use parental controls? My parents had router-level parental controls
well that was a silly thing to write.
If you are the parent you don't need to block scarleteen, or go ask alice, or whatever sex ed website you're thinking of.
Why can't parental controls block a game? it seems very plausible to me. they probably all connect to certain servers, use known ports or otherwise have recognizable traffic.
teach your kids how to not download malware, not get scammed, etc
can you please teach the rest of earth's population once you've figured it out