Midgard Eagle
Warlord
In this thread I will discuss a possible migration mechanic, in which the game would simulate real-world human movement patterns.
For example, if New York has 3 Unhappy citizens and -1 health, and Los Angeles has no unhappy citizens and is perfectly healthy, over time the population of NY would decrease while the population of LA would correspondingly increase, one population point at a time.
The more dire the conditions in a city, the more people would leave -- warfare and other dangerous situations would be the strongest incentive in the game. Depending on the circumstances, migrants would cross national borders into rival civs' cities, taking their culture with them. Citizens forced to flee could perhaps try to return to their origin city/civ when able, rather than staying in their new country.
Other contributing factors:
Players would be able to control their migration somewhat, especially when running authoritarian civics such as Police State. For example, you'd be able to attempt to keep people from fleeing the country (think the North Korean-Chinese border or the Berlin Wall), or decide that you wanted to limit immigration from other civs, or close your border to refugees. Maybe you could even have a mechanic where you moved your citizens into newly conquered cities to thin out their culture faster?
Perhaps newly arriving citizens could be classed not as Citizens but as Immigrants/Refugees, which could not work for one or more turns until they got settled in (a bit like angry citizens)? Masses of refugees carry with them a whole host of problems in real life, and could carry penalties like unhealth or a penalty to gold income.
I also think there's room for happiness and relations penalties/bonuses here. I picture xenophobic citizens giving you Unhappiness from immigration into their cities, or a friendly foreign leader giving you a "+2 You cared for our refugees" relationship bonus after you opened your borders to their fleeing citizens.
Stops all unauthorized migration into, out of, or through city. Prevents city from trading with foreign cities. Helps thwart enemy spies. Causes
.
Checkpoint:
Reduces unauthorized migration into and through city. Helps thwart enemy spies.
Ellis Island: World Wonder.
Greatly increases migration rate to this city when running Encouraged Immigration policy. Migrants and Refugees are turned into Citizens instantly.
Internment Camp:
Prevents unhappiness or rioting from foreign nationals.
penalty corresponding to foreign 
level.
Refugee Camp:
Reduces impact of Refugees, allows you to turns Refugees into Citizens faster when running Assimilation/Integration policy. Causes
corresponding with number of Refugees if too many are present in the camp.
For example, if New York has 3 Unhappy citizens and -1 health, and Los Angeles has no unhappy citizens and is perfectly healthy, over time the population of NY would decrease while the population of LA would correspondingly increase, one population point at a time.
The more dire the conditions in a city, the more people would leave -- warfare and other dangerous situations would be the strongest incentive in the game. Depending on the circumstances, migrants would cross national borders into rival civs' cities, taking their culture with them. Citizens forced to flee could perhaps try to return to their origin city/civ when able, rather than staying in their new country.
Other contributing factors:
- Civics -- Police State preventing people from fleeing country, isolationist policy preventing people from entering civ, etc.
- Geographical distance between cities
- Tech level
- Terrain -- it's far harder to leave a city that's in the middle of a jungle than it is to cross grasslands. Roads and railroads, and mprovements such as Harbours, would have an effect here, too
- Connection to trade network, and/or existing trade routes
- Safety of origin/destination cities -- for example, a city being constantly bombed would be vacated quickly
- Hostile military presence, level of fighting
- Culture and relations of destination city. For example, your citizens won't be that hesitant to move to a city where their culture already has a significant presence. Conversely, they'd try to avoid moving to a place populated by people they don't like, or where they're not welcome. If you're, say, playing as the Vikings and neighbouring Stalin's Russia absolutely hates your guts, your citizens will be less likely to move there.
Players would be able to control their migration somewhat, especially when running authoritarian civics such as Police State. For example, you'd be able to attempt to keep people from fleeing the country (think the North Korean-Chinese border or the Berlin Wall), or decide that you wanted to limit immigration from other civs, or close your border to refugees. Maybe you could even have a mechanic where you moved your citizens into newly conquered cities to thin out their culture faster?
Perhaps newly arriving citizens could be classed not as Citizens but as Immigrants/Refugees, which could not work for one or more turns until they got settled in (a bit like angry citizens)? Masses of refugees carry with them a whole host of problems in real life, and could carry penalties like unhealth or a penalty to gold income.
I also think there's room for happiness and relations penalties/bonuses here. I picture xenophobic citizens giving you Unhappiness from immigration into their cities, or a friendly foreign leader giving you a "+2 You cared for our refugees" relationship bonus after you opened your borders to their fleeing citizens.
Migration Building brainstorming
Berlin Wall: World Wonder. Requires Police State.
Stops all unauthorized migration into, out of, or through city. Prevents city from trading with foreign cities. Helps thwart enemy spies. Causes
. Checkpoint:
Reduces unauthorized migration into and through city. Helps thwart enemy spies.
Ellis Island: World Wonder.
Greatly increases migration rate to this city when running Encouraged Immigration policy. Migrants and Refugees are turned into Citizens instantly.
Internment Camp:
Prevents unhappiness or rioting from foreign nationals.
penalty corresponding to foreign level.Refugee Camp:
Reduces impact of Refugees, allows you to turns Refugees into Citizens faster when running Assimilation/Integration policy. Causes
corresponding with number of Refugees if too many are present in the camp.
