Preface |
I have been testing the game in observer mode and the end game conditions favour big empires versus small nations. In particular happiness for no clear reason.
Observation |
Happiness is not an issue at the end game with all the inventions and modifiers available to the players. For example, Egypt is at war and has war exhaustion, has negative stability, the priesthood was ignored, the governor is not of the primary culture, its paying more to the military, and has two other integrated cultures. Nonetheless, its population is more than happy and unrest is not a problem:

Of all the modifiers, the happiness increase for integrated cultures due to state rank is the most problematic IMHO:

Suggestion |
Integrated culture POPs will not be happier following the state rank of the nation. Instead, the player will have the option to add increased migration attraction to a newly conquered territory. Any integrated culture POP that moves to that territory will have a +20% happiness as this represents that the POP has been given land in the new territories.
Implementation |
Next to the move slaves action, a new action 'settlers encouraged' that cost 5 PI, will increase +5.00 migration attraction for a territory that has been recently conquered for 240 months. Any integrated culture POP that moves to this territory while this action is active will have its happiness increased +20%.

Existing integrated culture POPs in newly conquered territories will not be affected unless they move to a territory where settlers encouraged is active.
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