I have already started a fortress on a world where I tried VERY hard to extinctify dwarves. Somehow they survived, despite #civs being turned waaaay up, X/Y elevation variance being turned waaaaay down (removes cliffs, and makes mountain generation difficult), #peaks being set at 2, savagery being set absurdly high, volcanism set absurdly high, etc.
The embark is savage. It relentlessly spawns animal men and giant animals. I used dfhack's embark command to embark directly on top of a necro tower, and before unpausing, locked and forbade the doors, then built the fortress all around the necro tower, thus incorporating it into the fortress's design. It's inhabitants will be used to preserve the bodies of the dead in permanent unlife. (Gives me something !!fun!! To do while I wait for dwarves to become inbred idiots.)
I am gonna run with a few house rules.
1) nobody enters or leaves for any reason at all. There litterally will not be a door into the fortress.
2) the liason will speak with the mayor/baron through a fortification slit, via a tiny 1x1 room with a locked door. The meeting room will be an exploit: create an office in a 1x3 tube room, then install a fortification wall afterwards. This will allow the liason to get into one side of the office, and the noble into the other. The liason will never get inside the fortress, because the fortification will be in the way.
3) per the above rules, the trade depot is there just to avoid the "inaccessible depot" spam, and the caravans are goblin bait. Nothing more. They are to be ignored.
4) Goblinite will not be collected
5) only food, crossbow bolts and clothing items will be created inside the fortress, and only as needed. Mandate items will be created, then atom smashed or melted.
6) per 5 above, moods are disabled.
These rules are in effect to ensure total longevity of the fortress, since item creation is what usually causes the FPS death, and this fortress will have to run a very long time to complete the experiment.
As already stated, the fortress is nearly ready to be sealed, and the experiment begun. Fortress has 31 residents at the moment. That is enough to begin. The "dwarven consolate chamber" still needs to be constructed, but will be easy to accomplish.
Tomorrow I will begin candidate selection for honeymoon suite duty, and will post the lucky single's data for thread feedback and matchmaker services.