Hehe, while I do agree that this game is an excellent single player game, I would like to add that the game could play decently as a multi-player co-op game.
Ever play SAVAGE? That game was an extremely good multi-player game (well, when playing with friends). One player would take over the base setup, while the other players would take orders, go collect resources, help build, attack the enemy, or just goof around.
All players would play in a first/third person view, (btw, the vision I'm having right now about this is after DF gets funded and pops into the 3 dimensional realm, no matter how unlikely it is), whereas the leader, (whom the players vote as their leader) gets a map that they can use to set the area where the digging will take place, then can designate it from the map.
When I say map, I mean it would act like how DF acts now, top down, able to highlight areas for digging and the like.
Players can choose to do whatever they wanted, chopping down wood, mining, fishing, hunting, whatever you could do in the game. If the player wanted to take a break but everyone else didn't want to, they could set themselves to a drone state and go "afk" or log out and even shut down the game, the character would turn into one of the drone dwarfs, and do various jobs/tasks.
Speaking of drone dwarfs, there would still be a couple in the beginning to help mine and farm and that kind of stuff, you would set what kind of jobs they would do and in what order.
There is other stuff to say, but nothing I'd like to add right at this moment, >.>