>>876127/x/ is more like the conspiracy/schizo/theology board now. There's the occasional attempt to tell spooky stories, but it's mostly KotH Dale-style tinfoil hat. /tg/ has threads every once in a blue moon where they write collaborative horror, but you're better off scouring the archives for them. They're pretty good though, and you could probably attempt to start your own if there aren't any currently on the catalog.
http://suptg.thisisnotatrueending.com/archive.html?searchall=night+shifthttp://suptg.thisisnotatrueending.com/archive.html?searchall=urban+uneasehttp://suptg.thisisnotatrueending.com/archive.html?tags=horror 