The title, basically.
Aside from a few new video posts that crop up, the forum devolved into a handful of acerbic nerds, like myself, communicating with each other through inside jokes and nonsense stoner babble. We've reached that Realms of the Haunting spiritworld decorum and I admit that I'm partially to blame.
Personally I prefer any online discussion to be be as chaotic and open-ended as possible, but if this is driving new blood away, then I can tone it down a bit and try and act like a normal person. I would also encourage the other regulars (you know who you are) to do the same. Otherwise, it might just be that is format of internet discussion is dying out because of aggregates like Discord, which I think is a real shame.
I can't really think of other ways to revive this community apart from maybe announcing and holding a few gaming sessions and archiving(hiding) stale threads.