Realistic growth and travel

WARNING: The systems in this mod require setup at the start of the game. When the game starts, it will freeze while setting up the needed variables for several seconds. This is normal. Additionally, this mod is still under development, and likely has some balance issues.

Version 1.2.1 Released! Fixed several painfully major bugs in the prior release. I’ve posted some explanations of new features in the discord (look at stickies), but still need to write up full explanations. In the meantime, stop by the discord if you have questions!

Version 1.2 Released! Compatible with 2.0, feature explanation coming in the next few days.

Version 1.1 Released! See the new features here: https://imgur.com/a/vKAYv7Q

Mod discord: https://discord.gg/45SKZAx

Does the linear growth of pops in vanilla Imperator feel unrealistic? Have you ever thought it was strange that a depopulated farmland province produces more food than a decently populated one? Does the Imperator map feel too static, with people not moving into your cities unless you enslave them? And does it feel weird that country in Gaul can control territory in India without any penalty due to distance?

This mod attempts to rework these four areas that felt overly gamey to me by replacing them with new systems based on events and province modifiers.

The population of provinces no longer grows linearly over time. Instead, it grows according to a logistic model. This means that at low populations (relative to population capacity), the population grows exponentially. Completely unconstrained by pressures of food, infrastructure, or money, the population growth rate can get as high as 3%/year. However, as people exhaust the natural and artificial resources of their surroundings, the growth rate will slow down, eventually reaching zero at the population capacity. Should a rich region be depopulated by war, for example, the population will potentially recover much faster than in vanilla. However, unlike vanilla, the population growth will eventually taper off. Cities in the era were (probably) population sinks, and so large cities will actually experience negative population growth when near capacity. They must rely on immigration from the countryside to sustain themselves (see the section on immigration below).

In vanilla, food is produced by territory. In reality, it is produced by farmers on the land – a depopulated province will not produce food for the nearby city. Moreover, people tend to farm the most productive land first, eventually moving to more marginal land as population pressures grow. This mod sets the base food produced by territories to zero. Instead, a province modifier is applied to all provinces based on their population of non-nobles (nobles are assumed to be above simple farming).

The first pop in a territory will produce substantially more food than they need to survive. The amount more is dependent on the type of terrain; it is highest in farmland and lowest in rugged mountains and scorching deserts far from sources of irrigation. As the population grows, the marginal production goes down, until it eventually reaches subsistence level at population capacity. This production is modified for freemen, tribesmen, and citizens based on your available manpower. As you send away your young men to die in distant battlefields, productivity will fall to as low as 75% of its maximum productivity when your manpower is at zero. Additionally, building a mine or farming settlement indicates that the slaves are working to produce goods for export, and as such they will not produce food. Additionally, high civilization value provinces will have higher food yields and will therefore be able to support more/bigger cities.

Cities produce half the food of rural provinces, and only the first 20 pops will produce food. Metropolises produce no food.

So, for example, take a province with 6 pops and a population capacity of 6. Each rural pop eats about 0.2 food per month. The first pop may produce 0.4 food adding 0.2 to the surplus. The second may produce 0.36, the third 0.32, the fourth 0.28, the fifth 0.24, and the final pop may produce 0.2, just enough to survive. Above the population capacity, farmers will still produce food, but less than the amount they need to survive.

Pops in the mod will now move to nearby provinces just looking for a better life. The immigration attraction in rural territories will be proportional to the surplus a pop would get farming if they moved there (the surplus production of the last pop, as described in the section above). Attraction in cities is based on how far below the population capacity they are. That subsistence farmer may move to a nearby province will more room for profitable farming, or to a nearby city with greater opportunities. This will hopefully be expanded on in the future to incorporate additional factors.

Without modern transportation and communication technology, large ancient empires had great difficulty maintaining control over distant territory. Realistically, an empire in, say, Great Britain could not have maintained the sort of direct control over India in the ancient era that they could over territory closer to home. As such, this mod reduces the manpower and money output of provinces based on how long it takes to get from the capital province to this province through your territory or ocean/river provinces. This travel time is calculated by considering the provinces that must be crossed in the fastest route to the capital. The fastest route is calculated taking into account terrain and roads; the fastest route may be significantly further if you can go by boat rather than over rugged mountains, for example. Each unit of distance causes a 1% penalty in the manpower and cash output of a province. The distance is calculated as 0.5 (for sea provinces), 1 (for farmland and plains), 2 (for hills, forests, and deserts), or 5 (for mountains, marshes, or jungles) per province that must be crossed to get to the capital. Roads cut the movement cost by half (e.g. crossing a farmland province only decreases output by 0.5% rather than 1%).

• The addition of disease and plagues.
• Expansion of character interactions.
• Expansion of the travel time system. For instance, allowing routes through vassal territory.
• Tie governor loyalty and corruption to travel times to their province.
• Allow governors to attempt to break away as an independent state as well as causing civil wars.
• Expansion of the law system. For example, do you collect taxes through tax farmers, customs, direct taxation?
• Expand on the factors pushing and pulling people towards particular provinces.
• Create a travel time map mode (via trade goods)
• Possibly allow the seizing of occupied territory unilaterally, at the cost of relations with nearby countries and aggressive expansion. Certain wars would allow this to be done at much reduced costs, such as wars between the diadochi in the early years of the game.
• Make armies use manpower as well as money for maintenance. Those 1000 guys you recruited 200 years ago are currently still doing the fighting. Realistically, even in peacetime you need recruitment to maintain your forces.
• Improve the efficiency of existing code. For example, use binary search rather than a bunch of if-else statements for assigning modifiers.
• Suggestions from you!