So, after extensive modding and testing, I'm almost ready for my second attempt at a deep dwarf fortress. Currently aiming for an alternate, not-blatant-cheat way to create soap that doesn't involve lye. My thought was to make an extremely slow growing plant (akin to tree-length growth cycle) that could be milled into something that could be used in place of lye, along with tallow or oil, to product soap. That should have almost as many steps as lye-making.
As they're shaping up, my dwarves are delightfully primitive cavern dwellers. My attempts to phase out any industry that relies on burning fuel and metal is mostly successful. Bones can now be milled and processed for fertilizer, any reasonable sort of weapon can be produced from wood and/or stone, and armor can be bone or wood in addition to leather. Also attempting to devise a way to produce viable low-strength cloth-based armor (padding), primarily just to have a use for cotton candy, but the issue of wear has so far proven insurmountable.
My biggest success was ensuring that dwarves and dwarves alone would exclusively used cave creatures instead of anything from the surface. Large rats replaced dogs, crundles more or less replaced chicken or other fowl, and dwarves now employ large animals like giant olms or giant rats as pack animals. Most of them (not crundles) can also be trained, but they the more dangerous ones still cost just enough to make it a gamble to bring them along.
Repeated testing runs have produced some really interesting and strange things, some from the mods and some just from the randomness of Dwarf Fortress itself. There was one world where every first cavern level everywhere was a barren muddy hellhole. It looked as if they had been full of water that drained out. No plants of any sort ever grew there and for the most part only cave spiders and troglodytes lived there, along with displaced elk-bird herds. An attempt to mod scales into something tannable had the weird result of making skin and silk count as tanned hides and thus I had dwarves wearing clothes made from what I can only assume was still freshly damp elf skin hats. I had War Floating Guts and War Flesh Balls at one point.
The best one, however, was the Reptilemen Mercenary Squadron, led by the heroic and dashing Clasppedbanners (whose name in dwarven I cannot recall). They actually began as an intended effort in cave diplomacy when Clasppedbanners shot and killed a Forgotten Beast who appeared outside their camp (in one puff of his blowgun, no less), turning him from hostile to friendly. After learning from elsewhere on the forum that animal-men tend to turn friendly once they attacked enemies of your civilization, I embarked upon an effort to convert the entire tribe. This was an involved process, capturing goblin raiding parties,stripping them, and dropping them from just far enough above the Reptilemen camp to injure and stun the goblins without outright killing them or exposing my workers to blowgun fire. It took multiple raiding parties and despite their advantages, the Reptilemen still lost three of their numbers (one to falling goblins), but in the end I had seven friendly Reptilemen. After that, I lured them into my fortress with a string of helpless goblins. Once they were inside, they manned my forward fortifications and did good service against numerous threats. Claspbanners personally killed two more Forgotten Beasts, becoming a well-titled badass in the process (it was one of those rarely generated cool titles too, something like Sundering of the Silver Ice), while the others all earned their stripes against blind cave ogres and troglodyte raids. As a show of good faith, I had my dwarves bring all their camp goods inside, without stealing them.
I was about to begin seeing if I could get them to pick up and additional armor or better weapons, but sadly as seems to be the habit for Dwarf Fortress for me lately, a random crash cost me the game and erased it's history from the legends of the world. Still, in the future, when I'm done modding it up (possibly giving the animal men the ability to breed, though that might result in hostile children), I think I'll try more cave diplomacy on any animal men I see instead my usual habit of just killing them and stealing their stuff.