Happiness is calculated per city.
Each city starts with baseline happiness specified in new game settings (+5 by default).
Utopia upgrade increases this number by +1 each time it is built.
Additional Happiness can be gained as income from tiles and resources.
Happiness is reduced by:
City population.
Highrise upgrade reduces this factor by 50%.
Number of cities.
You eventually need to build Utopia in every city in order to continue expansion.
The number of unemployed workers.
Unemployement reduces happiness quadratically.
Each consecutive turn spent in poverty (no ⬤ Gold in treasury).
Starvation (negative Food in the city).
Starvation reduces happiness proportional to the city population.
Immigration.
The Void.
Happy (Happiness is positive)
gives Void Resistance within city borders proportional to Happiness. Happiness of +10 or more gives 100% resistance.
Content (Happiness is 0)
gives no bonuses.
Unhappy (Happiness is negative)
gives 50% penalty to city growth and 25% penalty to production.
Anrgy (-1 Happiness per population or lower)
gives 50% penalty to production and stops city growth.
Raging (-2 Happiness per population or lower)
stops all production and growth. The city will lose 1 population at the end of this turn.