World Generation

[Protolore]

I have been messing with the detailed mode, reading guides and forums, and watching tutorial videos. But I can't actually find what I'm looking for or figure it out on my own. I want to make a desert world, think mad max, and have tried every which was to just adjust the parameters but cannot for the life of me get anything but rejected worlds and if I allow it to generate anyway it ends up making a normal world. Any help would be greatly appreciated.

[Uncertain]

You're probably figured it out by now, but I was searching for this yesterday and later made something that worked, so for any Future People who might be interested:

I copied the Large Island setup (in case that matters), and set the following parameters (I don't believe those in italics are relevant, but I altered them from default so I'll mention them anyway in case I'm wrong):

Maximum rainfall: 50
Rainfall X & Y variance: 100
Minimum temperature: 0
Maximum temperature: 100
Drainage X & Y variance: 100
Rain mesh size: 8 x 8
Rain weighted range (0–20): 10
Rain weighted range (all other values from 20–100): None
Drainage mesh size: 8 x 8
Drainage weighted range (0–20): 10
Drainage weighted range (all other values from 20–100): None
Pole: North and South
Minimum volcano number: 5
Minimum complete edge oceans: 4
Mineral scarcity: 3000
Number of werebeast curse types: None
Number of secret types: None
Number of evil cloud & rain types: None
Allow necromancer anything: No
Minimum initial/final Wetland square/region count: None
Minimum initial/final Forest square/region count: None
Minimum initial/final Glacier square/region count: None
Minimum initial/final Hills square/region count: None
Minimum number of low-elevation squares: None
Minimum number of mid/high rain squares: None
Minimum number of mid/high drainage squares: None

The mesh size, variance and weighted ranges do almost everything as one system, although reducing maximum rainfall seems necessary in order to have the world comprise almost only deserts. The initial/final tile type minimums are just safeguards which prevent the game from creating worlds of this nature by default, so I removed the incompatible ones.

For smaller map sizes, I think the mesh size will automatically scale down with the map size, but the variance may need to be reduced further to give consistent terrain. I'm not at all sure about that though.

To work this out, I used this chart which describes the value ranges each biome needs:
http://dwarffortresswiki.org/index.php/DF2014:Biome#Generating_a_Biome

So I tried to clamp rainfall below 10 and drainage below 20 by enabling the mesh system for them and allowing only values within the 0–20% range in the mesh. I believe the weighted ranges refer to percentage chunks of the number range between the set minimum and maximum values, so with Maximum Rainfall at 50, 0–20% keeps rainfall below 10 in most cases.

Reducing variance, which I think is essentially noise that adds interesting random variation to the mesh grid's output, from 400 is to create more consistent desert regions.

This climate may cause unfortunate side-effects such as preventing elves from existing.