/x/ is the catch-all board for the obscure, supernatural, abnormal and bizarre, and as such, its scope is very wide. Though it's all spookbait, it has the potential to be interesting.
I haven't found any information on its history, but I presume it was formed as a splinter of the original /x/ when 4chan migrants settled the site.
CSS is dark, with humorous banners. One suberb detail is that default names are constantly changed by the BO. As you check older and older threads, every poster will be called "Uncaring Cosmic Abomination", "Reptilian Overlord", "Nosferatu", "Kelpie", "Skinwalker", "The Master of the Monolith", "Kraken" and so on.
Rule #3 states that /x/ is an apolitical board. Conspiracies about shadowy elites and government tyranny are discussed but ideological themes only appear insofar as they're relevant to the board's topic.
Language and levels of politeness are standard, not different from any regular board. Despite the board's tone, many posts and even entire threads are made in either a realism-minded or a lighthearted mindset.
Threads are made about all sorts of things. I'll list a few I've examined:

">tfw no vampire gf" thread. The finer aspects of romance and sex with vampire women are discussed. Later on someone talks about killing vampies with stake-firing shotguns and holy water cannons, and the question of wheter vampires are material or metaphysical beings comes into fray.

A supposed Serial Experiments Lain-themed suicide cult imageboard. A link is actually given:
https://boards.systemspace.link/
I checked it out and there are still living posters, so I guess they didn't kill themselves. I've earmarked that board for later examination.

Men in Black. Someone says they are supernatural but only exist in the viewer's mind, and are merely omens or messages.

"Reality glitches", small events in day-to-day living that don't make sense. Very banal.