Just as some of us pointed out, the density indicator may not work properly in some cases.
For example in FEI, the infected realms are losing players constantly. Number of characters in Kindara has dropped from ~45 to ~30. In the following week, I believe this number will continue to reduce. Will they move to other regions in FEI? I don't think so. These natural disasters will likely to make some of them to leave this game world.
When they leave, the density will drop again. Will the dev team advance the glacier again? That would be ridiculous.
If the glacier thing is affecting the west side of the continent, then at least the nobles can join their allies. Now the ice age and the military oppression may likely leave these nobles no choice but give up.
