Anchor, or "Anke", seems to be a chinese language community over on Baidu who run something similar to what we'd know as forum based CYOA/Roleplays, in similar function to the early MSPaint adventures, or if you spent time on forums, threads where a writer would put forth a scenario and allow the audience to make choices guiding the structure/direction of the story. If you're curious, you can find the community by searching 安科吧 on google and selecting the first Baidu result. Anke seems to focus primarily on fandom crossovers from manga/manhwa, games, movies, and etc media, and rather than audience participation, the author will allow random number generation to guide the structure of their story, similar in which to tabletop rulesets allowing degrees of success/failure.
Anchor Club, for it's part, seems to offer an alternative framework to forums / baidu to create, write and run these scenarios (and share them on for others to view and enjoy and comment on, similar to things like early MSPA, Prologue, etc) while allowing people to view them as they're being written with it's 'rooms' system. The interface seems to be pretty handy, and whilst I appreciate the english translation, given english language resources on what this is and how to interact with it/run a thread of it are pretty much nonexistent, if they want english adoption they may want to include an introduction of what Anke is and is for.
That said, if this piques your interest at all, I do recommend poking into the Anke Club Baidu with some web browser translation and digging through, whilst my understanding is baseline it was quite fun to dig in and see what's going on here. As a writer I imagine this form of writing exercise could be quite fun as I do have fond memories of running similar things on forums here and there in my teens.
In summary, think of this as a collaborative, random number generation driven fanfiction writing exercise tool created for a community with a pretty deep history of works. Or simpler, AO3 crackfics with added RNG in the writing process. It's pretty inaccessible for an english speaker, but hey, if you're a bit odd like me and enjoy digging into strange places on the internet, this should hopefully get you looking in the right direction.