Relytor’s Biological Proliferation
Realistic Logistic Biological Growth
I’ve wanted to change the pop growth in Stellaris since it first came out. Thanks to Starchitec’s Carrying Capacity, I saw it done. There are some things about his implementation I wasn’t real keen on, however, so decided to create my own.
In vanilla Stellaris, pop’s grow at a linear rate: a base speed of 3/100 pops per month, or 0.36 pops per year. In realistic models, life grows exponentially: the more organisms that are reproducing, the faster the population grows. This give a growth rate as a percentage of population per year, rather than a set amount. But this infinite growth is diminished by finite resources: living space, access to food, etc. This diminished exponential growth gives an S-shaped logistic growth curve, which grows to the maximum population amount the environment can support, called the carrying capacity.
In the future world of Stellaris, I assume you can always produce more food and other resources, so only consider living space as the limiting factor of growth on a planet. The living space that is left on a planet, the number of biological pops, and the total number of pops, all determine what the current growth rate will be on the planet. In general, when a planet is at half it’s carrying capacity is when it grows fastest, while the rate diminishes to zero as you approach 0 pops or the maximum amount of pops. I chose a growth rate of 2.5% per year, as that gave a curve that reached the half-way point about the same time as vanilla linear growth would, if you start with 2 pops. Because of the nature of logistic growth, the more pops you start with on a colony, up to half the maximum pops, the faster pop growth will be. The first few pops make a huge difference, so starting a planet with 1 pop will grow much, much slower than a planet starting with 3 pops.
The base monthly growth was changed from 3 to 1. Any growth bonuses are added to this to get the base growth rate. A planetary feature on the planet, called Limited Planet Resources, will apply a penalty or bonus to the base growth rate to get the final monthly increase. This modifier is called Pop Growth Reduction, and is meant to be a growth penalty applied to the base growth plus all the other growth bonuses. As such, if this is from 0 to 100%, it slows growth until it stops completely at 100% Pop Growth Reduction. But, if this is negative, it actually turns it into a Pop Growth Bonus, even though the name of the modifier doesn’t change. So a Pop Growth Reduction of -100% would actually double the growth on the planet, including the effect of any other growth bonuses.
This should be compatible with any mod that doesn’t change the basic population growth. No vanilla files, events, or anything else was overwritten. If you start this in the middle of a game, the deposit will show up as soon as you build or destroy a building or district on the planet, clear a blocker, terraform it, or most anything else that changes the available districts and/or total housing. In addition, sometime in the first two months of the year, every colonized planet will get updated and get the deposit if it doesn’t have it.
Empire United, a Unity system Overhaul
Empire Governance, an Ethics and Civics Alternative (alternative Cultural Overhaul) sub-mod
Planetary Overhaul, a Planetary Diversity sub-mod
True Raiding, a Barbaric Despoiler/Nihilistic Acquisition mechanic overhaul
Revisions:
Old revisions of this mod are available below. Click the link to download.
