I originally wanted to determine realm parameters that would make playing fortress mode ridiculously easy, than I decided after realizing something to generate a world that is as rid of evil as I had a patience for it. I was doing that without any mods.
It only has 3 biomes: Mountains (for river reasons), both types of forests and swamps (for river reasons).
All the tiles are non-savage and good. I could generate only elves in this world. Hopefully they are biologically immortal.
To completely disallow access to the caverns underground I had removed all caves. Forgotten beasts should at this point truly be forgotten. Cave creatures should also be isolated from elves.
Volcanic activity is also abscent. No magma monsters.
History generates up to 10000 years but you can pause it and ignore large amounts of time progression.
There should be 40 civilizations every time you generate it. Between 0-100 rivers are generated. They should be long.
The only concern I'm worried about is the fact that alligators are sometimes killed by the elves, possibly because they kill innocent animals. It also takes a long time for the world to form in the river phase for some reason.
If by any reason you feel offended by this world having only elves as civilizations you can remove part of the good squares and hope for neutral mountains. Only elves can start from good biomes. Dwarfs should be starting from there. Humans need at least one of the following biomes to start existing: Grassland, savanna or shrubland. Kobolds cannot exist without caves and goblins are abscent with 0 demons.
https://jumpshare.com/v/lWD46kiQW2tVrSq1oaOv