- Aboveground-only farm workshops, like dairy farm, agriculture monocultures and mills.
Is it have chance to include animal farm? Build workshops (with bureaucratic permission, written with inks and some rare ingredients on paper to keep it late game buildings) wich produce yarn, cheese, and even scales (also require blueprint available from dwarves), chitin (drow contract) for example, to reduce amount of animals from 500+ to reasonable amount and save late game fps? Well, ability to purchase all this with coins via some trade house also fine.
I have zero experience with DF modding, so everything below just ideas, which
probably possible to implement.
Diplomacy - option to invite "enemy of my enemy" to repel invaders and leave items/corpses on ground much more appealing, but I afraid they will just camp map edge forever even if it possible.
Witchhunters - let them have own workshop. To send them in wilderness to hunt foul sorcerers and develop own magic in fortress with occasional loot they bring back (absolutely not foul, even this +dwarf cultist skin cloak+ as pure as childs tears. Our fort specializing in child's tears, ya know?) Of course they aren't interested in gold, but will gladly hunt whatever you want with orders (paper and ink to create one) from.. yes it's some bureaucratic structure again.
Caves, tunnels, underground - is it possible to add some kind of autospell to every human which spawn some faceless terror if he spent to much time underground (linked to cave adaptation, which even orcs have it seems)? Well, idea to make them appear in tunnels below surface, rip human apart and leave misleading message in combat log like "Peasant X suddenly noticed CreepyShadowHorror lurking in darkness" instead of "Peasant X summoned CreepyShadowHorror, which actually hostile / opposed to life". But opposed to life can be abused imho, so hostile to humans only civ should be better, but no idea is it possible or no.
As for gameplay aspects - take away magma from humans, let them order/purchase some fuel in tradehouse and give them bureaucracy. Dwarfs can pour all they see with magma, orcs can fight all they want, kobolds all about survival and short lifespan, warlock about sorcery, humans.. humans could do all this but they don't have permission in 3 exemplars signed by Gran Councellor, verified by Scrivener so..