I started a fort where my original seven dwarves sealed themselves off from the outside world after misinterpreting a passage in the Dwarf Bible. So, no migrants, no trade, no going above ground, and sealing themselves off from the world as soon as possible. No animals allowed, either, as the ones underground could potentially fornicate with those on the surface through dark magic. The camel stallion my dwarves came with was promptly slaughtered, and its meat and entrails are stored, but largely unused.
I embarked in a box canyon in the desert with a stream but no aquifer. I created a totally impregnable defense by channeling out an artificial lake with a hatch on the bottom (that doubles as a self-destruct mechanism) and a door rigged to flood the dry lake. After that I built a floor over the ramp leading to the channel that fills the thing, and mined out the edges to remove the ramp.
I had my population cap set to 0, thinking that since the pop. cap is set when the first caravan comes, and migrant waves are allegedly never any larger than your population, that this would prevent immigration. It didn't. I got 2, 1, and 4 migrants in three waves, and they all died a horribly protracted death in the desert. They could get water from the stream, which had nothing dangerous living within its depths, and pick up rats off the ground and eat those whenever they got hungry. Eventually the ground was littered with rat remains and patrolled by hungry dwarves. Eating rats didn't fill up the dwarves, as they were still hungry after eating them and they ended up quite unhappy. What finally killed them was that the river froze for a period in the winter, just long enough for them to die of thirst. In theory, dwarves may now be able to survive off vermin and water indefinitely, provided they aren't nobles (I've tried that before in 40d with predictable results).
Traders will now wait for you to build a depot if there is none. They can also apparently go insane if they're waiting around long enough. At least elves can. Interestingly, the trader's
horse went insane from boredom or from staring at the shriveled and dessicated dwarves lying next to a flowing river, and the elf he came with went insane immediately thereafter. Or it was the other way around. I should have been taking notes.
At the start of year four all of my dwarves are friends, or failing that "long-term acquaintances."
I embarked in the year 13, and all of my dwarves have the tag "...is among the first of his kind" on their bio page. All of my dwarves "
have the appearance of someone who is (55-88) years old." Dwarves are apparently
created by the gods as tiny old people.
No one's married yet, although that may be due to the year or my 0 population cap. Ideally my fort was going to turn into dizzying catacombs filled with cruel traps and bejeweled furniture populated by the horrifically inbred descendants of my original dwarves, but it's not looking like that's going to work out too good. I've heard that dwarves can inherit various traits from their parents and there's some kind of genetics involved in DF now, so it would be interesting to see if after a couple generations of cousin-marriage my dwarves end up like
Charles II, the inbred Spanish King who blamed his deformities and mental problems on witches.
Since my fort's reasonably stable and I have enough shiny things lying around to keep my dwarves happy, I'm thinking of raising the population cap and doing absolutely nothing else to see if any of them get hitched.
Also, about skill atrophy: it only takes 1-3 tasks to get from "rusty" or "very rusty" to normal.