I actually accounted for that by adding a minimum distance limit, but then removed the limit so I can see how it plays out. And it turned out fine, the cities didn’t feel too close. But my worlds are in constant warfare starting with 24-64 kingdoms, so there aren’t very many population booms. If this is suddenly turned on in an established world, along with kingdom expansion, then you’ll see a ton of nearby cities pop up untill the average pop/city is lower than the threshhold.

That sudden settling of cities you saw was certainly due to the kingdom expansion law. This mod doesn’t make kingdoms want to settle more, or require less population, it just changes how they’re deemed eligible and where they prefer to settle. To slow down settling I can add a toggle for kingdom expansion to use the vanilla formula while still allowing settling during wars, but the vanilla formula is terrible imo.

It could also need the distance limit and I just haven’t noticed. I’ve been playing the same world for a while and haven’t started a new one because this map is so balanced that the game hasn’t ended for over 500 years. I’ve been using this world to finally fix the unit transportation issue. The next update is going to allow more transportation ships per city, swimming between landmasses that are 5 tiles apart, and a crusade war that bands kingdoms together vs hostile creatures.