Fallen London is more of an ongoing CYOA with plenty of padding than a game, so once you run out of free content it runs purely on the strength of its universe (paid stories, Sunless Sea/Skies, etc) and the (hopefully) charming community.
I am fairly certain player interactions work even if you reply to them several years later, but they aren't that interesting by themselves until recently, and even then it still leans on both parties putting the effort in to RP.
The Scroll of Taiwu! Of course Nyaa is already doing a LP of it ?
It's probably the most depraved game I have seen so far, though, both on NPC and player behaviors. It is a Wuxia game on the surface, with elegant Chinese prose and full of wholesome inane life skills (no Greengrocery and Drive Carriage, but close enough), but NPC tends to enjoy autonomous crime, adultery, incest, graverobbing, while the player quickly degenerates into being a bodysurfing horror that eyeball anything as their next prospective suits of flesh.
There's already horror stories where a player poisoned a friend, tracked down the friend's reincarnation, adopted the friend, gave the friend plenty of support and sent them to be a Shaolin monk, only to poison the friend once again when they became a famous monk, tracked down the reincarnated kid once again for the grand finale of hijacking a body with some measly Kung Fu that get stronger based on the karma of previous life.