Currently the issue is content.
Idea is to strip out everything and rebuild from scratch. Dwarves will be left unaltered, but every other creature, plant, and material will be altered. Excessive use of corpses as resource intake will be encouraged and extreme scarcity is the name of the game. Every bit of resource will be important and cared for.
First, wood will be extremely valuable. It will be a rare resource, flammable and prone to rot, it will be a luxury item that not many have seen, much less own. Beds, therefor, will be a high luxury, and those 3 logs from the starting wagon will be all-important. Sadly the wagon can't be modded... The source of trees will mainly be an "Ent" type of monster that gives a log or two when butchered, and from farming, where a very long-term crop will produce usable logs of a certain type. That will need tweaking to make sure it's properly valuable.
Second, food will be scarce. Farms will probably take 2-3 seasons for a crop to be harvested, and seeds will be less than plentiful. Meat will be a large source of food, with most animals being slightly toxic, utilizing the new ingested syndromes to cause pain, blindness, vomit, etc. Temporary illness... mainly. All animals will be slow to mature, very hardened, and produce a lot of low quality meat, along with some other non-organic items.
Third, all other resources will be scarce, but huntable. Stone Bison will produce usable boulders when butchered, copper mechanics will be robots which drop mechanisms and copper bars when butchered. Fuel will be more plentiful, with most items being burnable for coke and letting you do things like converting leather into kindling, so smithing should be easy once you manage to actually get some metal. Ore Crabs are planned, rare, expensive creatures that can be sheared like sheep to produce ore and gems, and can be butchered for immediate resources.
Fourth, everything is a bit tougher. Or a lot. Meat is toxic, the local plants transform you just a little when eaten, and any creatures left alive have been weaponized by evolution. Hides hard as stone, metal horns, jaws that can crush armor, and massive size.
So, with that in mind, I'm harvesting ideas. What sort of creatures would be fitting, what would they be like, and where would any resources come from? There will be no mining, the only soil type will be named "Slade" and be undigable, but this will allow farms to be built atop the fake-slade.