Feeder colonies (limited to mine/farm/generator districts) vs developed colonies (which consume monthly unity) - upgrade/downgrade via planet decision

[Pancakelord]

One thing I've wondered about is making "new colonies" more distinct from "Established colonies"

Outpost Colonies
You can colonise anything, as now, but you are capped to only building farm/mine/generator districts on these colonies- and an "advanced colony outpost appears at 10+ pops for some extra basic jobs.

These colonies have reduced sprawl and automatic increased emigration push when maxed out/without open jobs. A planet decision could switch off immigration to this world when it's full, to better direct worlds to industrial/science hubs.

Established Colonies
If you want to build cities, industrial districts, science buildings or use more building slots, you need to spend (say) 100 influence, or 500 (scaled) unity - or take a running unity upkeep, to upgrade from a colonial outpost to a world with a capital and advanced building options (so each new "established" colony costs flat monthly unity).

Automation and Gameplay loop
I have found that when you constrain a colony to just building farms/mines/energy districts, the Automation (and AI) actually does a decent job. This lets you pretty much turn feeder/core worlds in to a real mechanic, rather than just what we all do in 3.0 to deal with the pop growth system.

Much of the early game would be spent building your capital, with a few ancillary feeder worlds. later you could upgrade/re-format feeders in to industrial hubs.

Early wars may move to visualisation over conquest if your unity production is low.
Annexing a well developed enemy capital early on could send you in to massive negative unity production (which could lead to civil wars, trouble occupying worlds etc), and would instead promote vassalizing/tributising such colonies, or running a toggleable planet decision to "give them autonomy", which reduces their output of 2nd tier resources by some large %, but reduces their unity upkeep too.

Performance
On the performance side of things, I'd also entertain the idea of reducing housing and #jobs from farm/mine/generator districts to 1 instead of 2 (and doubling all properties from those jobs to keep things balanced-ish) for planets [2.5x for habitat technicians/miners] [ringworld numbers unchanged].

AI optimisation (Outpost colony > Established colony)
Due to there being a clear line on what an outpost is vs an established colony is, rules can be written in to the Outpost > Established decision, to automatically guide the AI to

1. only consider upgrading a feeder world if it can afford to (no more lack of food, minerals or EC)
2. only consider upgrading a feeder world if it's growth isnt unduly affected (no low-pop AIs)
3. chose what kind of world to up grade in to - for example, the AI could be told to
   1. make a Tech world if its sci output is low VS neighbours, or if it doesnt already have 1 good Tech world in that sector.
   2. or an Industrial World if its alloy output is weak, but its mineral output is high

Scripting wise this would be done in a similar way to how ecumenopoli (in LEM) will automatically give you some forges or factories, or a mix of the two, depending on what the planet spec was set to before the ecumenopolis decision completed.

 

[Pancakelord]

A quick example of the ideas in OP:
Planets will not have their final districts shown, until a planet decision is run to add it to the list - changing this later, e.g. from forge districts to tech districts, (not shown) would cost minerals = new_district_cost * num old districts.

Currently testing this with

1. Industrial specialisation (allows forge or factory districts)
2. Tech world -- Research districts
3. Cultural world -- Unity building focus (theoretically a Temple district, too).
4. Processing World -- 'Advanced' Mining Planet designation + Refinery districts
5. Farming World -- 'Advanced' Agri-world + special farming output options
6. Generator world -- 'Advanced' Generator world
   • Where advanced means increased output via colony designations.

Decisions can have complex flagging and logic applied to them, as such, its possible for an AI to "read" how many districts a world has + how many (say) farm districts it can build, and then make a weighted judgement (e.g. if farms >50% max districts) to immediately specialise in to being an agri world.

• With a second event running once all farms are built (if farms =/= 100% max districts) for it to then pick a "secondary" specialisation for the world. e.g. filling the rest of district slots with cities or forges.
• When taken with the above 6 specialisation options, AIs can specialise their worlds quite easily AND it lends more weight to players' specialisation decisions, as districts and colony types only unlock when certain decisions are picked (e.g. no tech world designation if youve specialised the world in to a Cultural world).