Gunsmoke 3 had a fair bit of lore that wasn't all too easy to swallow in one go. Not to say the depth was bad, but the sheer amount of stuff can be daunting to new players. Shame it died though, apparently bad decisions on transitioning to a new map and system, or something.
And Begotten was a locked gamemode open only on set intervals, IIRC. Another horror-ish gamemode I can remember was something called Respite, I think? Idk,
@TheSandiestcomet recommended it to me, he probably knows more. And yeah, that gamemode died too.
But I agree, some unique ip would be dope as hell.