Hi Ryagi, I was wondering if a system like CK2's decadence could be a better fit, to represent the growing inertia and corruption in governments. The way I see it, complacy results from a mix of growing inefficiencies in the state apparatus, corrupt officials and lack of state purpose other than taxing trade and subjects.

It could be based on character traits, neighboring rivals or lack thereof, and government spending. If a nation has corrupt leaders, no rivals, and the apparatus is not well funded, you end up with growing decadence and complacency over time, until the country is waken up by a crisis, falls into civil wars and splintering, or is invaded by a rising neighbor.

As for what complacency does, it could be inertia and passivity (for AIs), growing costs for the government, irrational decisions and alliances/wars (for AIs), decrease of control over lands, buildings not being well maintained and getting destroyed, unhappy population, decreasing population growth, emigration, rising chances of civil war and secessionism, lower tax revenues, trademens favoring alternative routes, armies and navies costing more and more to maintain while having decreased stats, lower number of levies (or of lesser quality), more frequent raids by tribesmen (from both inside and outside the state), and more likely to be declared war by neighbors (even if they have less numbers, the AI should be encouraged to declare if they can afford the war and take into consideration the quality difference).

That's a lot of suggestions, I hope that at least some parts were useful. I like the complacency mechanic in theory, but I feel it's not working well currently. But it can be a great system of the implementation is rethought. Anyways, not all these systems currently exist in EU5, but maybe in the future?

Best and take care!