Factorio Forums

Save here:
http://sc2.ic.cz/creeperspawn.zip

Load, run left. Suddenly, 2 creeper bases appear. I am not entirely sure it's a bug, but it probably is. The bases appear only if i walk to them, in an area that was clear, a while ago i was putting electric poles there. I don't think any outside creepers walked there, because the area is inside of my perimeter of turrets, and though there are some holes, turrets would probably lure all biters to them.

Thanks, I will have a look at the save, though not right now.

It's possible that there were some biters on their way to build a new base at the time you finished the defences. In this way they could sneak inside and start building even though the position is no longer valid for them.

In 0.8.0, the conditions for making an enemy expansion will be even more strict. Additionaly the biters will check if the position is a good candidate once more before building at the place, so this kind of "we chose the place first" behavior should not happen.