Factorio Forums

As I understand, biters expand only once per 4-60 minutes. Which is on the lower side, given that the map is huge. Do the only expend on the explored terrain?

Afaik, from my own observations (so take that for what it's worth), they will expand on generated terrain. It doesn't have to be have been charted (explored) or under active site.

Found that there are show-enemy-expansion-candidate-chunks and show-enemy-expansion-candidate-chunks-values in F4, though they are more about proximity to nests.

Given that it is possible to have multiple "forces" in Factorio, each with their own set of "explored" chunks, even defining "explored" is non-trivial. My understanding is the same as Fury, they will select from "generated" chunks, even if your force hasn't charted it. Generated but unexplored chunks can either be caused by the pollution cloud or by the game always trying to keep a few chunks beyond your explored area pre-generated.

You have also hit on a "meta-gamey" point, the expansion timer is global, so the more of the map you have forced to be generated (by exploring), the more likely the biters will expand into an area you don't care about rather than one you do care about.

The other thing to realise is that the expansion timer is not random within the range, it's influenced by the evolution factor. So you *don't* get an expansion every 32 minutes on average. Rather it starts around once an hour but by the time you are up to green biters it's closer to every 4 minutes.