I like to turn my difficulty settings up. When I was playing the game seemed a lot easier than normal. Does this mod change difficulty settings? I built my base underground, which contribute to why, but the evolution rate seems a lot slower in all categories (time, pollution, nest kills). I turned them up 20x or as high as I could, and I'm just reaching .9 evolution after 46 hours, which seems like far too long.

It shouldn't change the difficulty settings, however I assume the evolution factor will be a lot smaller if you put all your factories underground and no pollution manages to get overground. From when I played the map, the evolution seemed fine, but I might be mistaken.

What do you think? Should there be a constant pollution outside to make sure the critters keep evolving?

On the contrary, I felt that underground was too safe. I think if enemies would sometimes respawn towards the edge of the explored zones it'd be more appropriate (if that's possible). Scaling enemy regeneration with pollution would be cool. Perhaps make the scaling quite aggressive, so that I'd feel compelled to work up top. The rocks significantly disrupt enemy spawning, so my overworld was ridiculously dangerous, but underground only had some moderate nests on the periphery. I'll admit I'm running other mods that made it easier as the game went on,, but nothing super cheaty until you can destroy nests, and by that time, it's usually pretty easy

For the overwhelming majority of my game I built everything underground, and grabbed solar panels as soon as possible. My overworld had no pollution until I put down some stuff for building the rocket. Adding pollution to all labs might be a solution. Emphasis on all because I'm running some modded labs (pollution_scale * base or current research speed?)

Now that I know a bit more about Lua, I went looking for why things weren't being set. In maps\caves\surfaces\overworld.lua and cave.lua, the surface.map_gen_settings table is being defined, not changed. That messes up any existing changes (as far as I can tell that's what's happening, or something like it). I was playing with overworld.lua, and by defining the resources in a table, and using pairs() over it with the autoplace settings (surface.map_gen_settings.autoplace_controls[key] = value), I specifically changed each resource. I completely removed the other settings for my tastes, as well as the enemy nests from the resource table. This time the map respected my enemy frequency/size settings (commenting out the enemy nest line in the table seemed like it reset it to default/normal game settings i.e. quite sparse and small).

I also have another two mods which adds ores, but they spawn up top. I might try adding a pairs() over data.resource, and see if I can move them from the overworld to the underground. It's more sensible than exactly specifying what resources you modify (and I see there's code for Bob's ores and stuff - that's not necessary if you loop over data.resource)