For the past couple of days I have been thinking on an idea. What I want to do is start a thread where seven people claim a starting dwarf. I play the game but they decide what their dwarf does.
I gen the world in secret. The initial embark points are evenly divided. Each dwarf can use their points as they see fit. Points can be pooled for items like the anvil. Questions about how the jointly owned items are treated and who owns the products made with/from these items must be addressed before embark. A simple solution may be to embark with one anvil and enough ore to produce 6 more, or a single breeding pair with the understanding that eventually everyone gets a female of their own. Then when everyone has one there is no question of who owns what and what to do with the community property.
New players are added as migrants join the site. The initial seven decide what to do with them. They can be forced to fend for themselves or added into the fort depending on if they have useful skills or a willingness to work the mine.
All public activities are to be posted to the thread. If one dwarf wants to extend their living area by mining they post a quickfort compatable text block to the thread. Everyone else gets a chance to review and object if they want. I do not resolve disputes. The group elects one member for that job.
I anticipate things going sideways and I plan to treat each dwarf as an independant unit. What this means is if someone PMs me and says, "I steal the anvil and secretly make my own" then I will have their dwarf walk over and take the anvil. It is up to the players to notice the anvil missing and to investigate.
Trading. I will treat trading like a swap meet. Each dwarf may put up items for trade and each trade will be made seperately using their dwarf to make the trade. If the group agrees to have one dwarf make trades for all then the group has to decide what to do with the profits. Once again, I am not the person who will resolve disputes. If two dwarves say that they just take the silver bar recently purchased I will flip a coin to see who gets it first and then have the other one steal it the first chance they get. I expect a lot of PM messages about how everyone reacts to this situation.
Trading between players (including new migrants). Both players need to PM me with the transaction. It may be enough for just the giving player to say, "I give one of my booze barrels to that guy" as long as it is not a trade. I'm expecting something like, "I give one booze barrel for six flux stones" with the other guy saying the same thing but in reverse. Once again if the booze is something that the fort shares ownership of then all I need to know is who is a member of the fort. Also, I am not responsible for the actions of thirsty dwarfs when one of your booze barrels is left out in the open. You'll need to address fair compansation with said dwarves' player.
I have some ideas on how updates will be made. One is to upload a file of the embark site periodically. Another is just to upload pictures. If anyone has any good ideas please post them here. Even a bad idea could lead to a discussion that produces a good idea.
You may ask why am I doing this, well it's because I'd like to see something like this done in a more official way and I see making a shared fortress as a way to show not only how it could be done but also that there is a real interest in a muliplayer mode like what I've described here.