In his research for the game Adams learned that in the real world when warm, wet air travels up the side of a mountain it loses moisture. Rain precipitates out creating areas like rain forests and snow capped peaks. On the other side of the mountain deserts form in areas that are called “rain shadows.”
So Adams built a custom algorithm that simulates rain shadows in Dwarf Fortress, and if you watch carefully you can see it.
The whole map will shudder and shift, just for a moment. All the biomes suddenly snap, a dramatic shift from east to west. Some shrink, others expand. Deserts appear out of nowhere. That’s the rain shadows kicking in.
In the future, Adams hopes to add plate tectonics. When he does entire regions of the map will be able to cleave against each other to create fissures, or smash into and over each other to become mountains.
"If we had land going up and down," Adams says with a sigh, "maybe none of this would be necessary."
By this point in world generation the game is using something like half of a modern quad-core computer’s total CPU power. It will hold there while it begins to spool up the maximum allowable amount of RAM that the game engine’s 32-bit software will allow. And it’s just getting started.