The Un-Men spun out of Swamp Thing, answering any questions you might have had about where Arcane’s grody little creations ended up. House of Mystery takes its title from the classic DC horror anthology book (and works in kind of the same way, but with more ongoing plot threads, I think.) They’ve both been added to the DC Reading Order as of this update.
We’re currently at 1264 books for Marvel, all with their contents worked out and most with dates. On and on and on! I’ve been doing it parallel with Self Contained books and other smaller orders, but I think I’m gonna pause that stuff for now to concentrate on getting Marvel worked out.