Every succession/community/challenge I try dies. I really wish other people had finished
the Hermit Challenge. That one told a wonderful story, where the game constantly hinged on the little bastard taking breaks at the worst times, an early-game cat-based defense strategy, capturing a female cyclops and being confused because that was his only female contact for a decade, and eventually capturing a web-spinning titan and knitting titan-silk socks. I never even got to post it because nobody else finished.
I've thought of a challenge where 4-6 players rotate the turns and control physically separate mini-forts across the map, keeping their dwarves in their own section via burrows or blocked paths, and during the current player's turn, the other player's mini-forts are left to run without new orders, so most of the time, each mini-fort is on autopilot. You'd need a carefully set up initial state so everyone can get their forts running, and at least some rules to prevent obvious, boring forms of sabotage. (including some FPS preserving measures.)
I think the loss of ambushers and the unreliability of invaders hurts newer versions of the game in succession forts, too. Getting enough interesting enemies to show up in the vanilla game is a big problem.