Greeted by ~75% spam—or so I assume—threads about Fortnite, PUBG, CoD when I just visited, I was reminded of an old mod which Zenforo dev Kier wrote for vBulletin back in a previous life, and since adapted for Zenforo. If PCG admin/mods aren't aware of it, it might help make your task easier.
xenforo.com
There was also some variation(s) of Global Ignore mod(s), but I can't recall anything about them at the moment.
Of course, many of these posters may be bots—I suspect they are—in which case such solutions won't have much/any effect. I don't know if there are mods which will look for keywords in new thread titles and auto-move such to a 'Limbo' forum for mods to check before releasing any legit ones into the general viewable forums.

Add-on - Tachy Goes to Coventry
Any add-on with vB's 'Tachy Goes to Coventry' functionality? Is it too difficult do develop for XF?

There was also some variation(s) of Global Ignore mod(s), but I can't recall anything about them at the moment.
Of course, many of these posters may be bots—I suspect they are—in which case such solutions won't have much/any effect. I don't know if there are mods which will look for keywords in new thread titles and auto-move such to a 'Limbo' forum for mods to check before releasing any legit ones into the general viewable forums.