This will be the last "brainstorming" post, since I think I've resolved all the issues. The good news is, racial population limit on different planet types can be implemented! Here's how it will work:
Instead of having each region be managed individually, all of the same regions are lumped together in one slider for each race. So if you have two mining and one research regions on a planet, there will be only one mining slider and one research slider for each race.
But what about population limit? Let's say that for Zero People in Arctic type, they have 15 limit per region, and humans have 5. Each region have "10" space, and the space is equally divided between the two races, and there are 4 regions on the Arctic planet. So there will be 30 zero people and 10 humans on the planet.
Let's say that the planet has two mining regions, and two others. If I assign 100% of the zero people to mining, it's 30 people in the mining. If I assign 100% of the humans to mining, it's 10 people in the mining. However, what if I assign more than the regions can handle, say, 100% of both zero people and humans in the mining? This is where I take the idea of MoO 3's diminishing return here. For every unit of population up to the maximum capacity, they produce the full capacity. Then for every unit of population up to twice the maximum capacity, they produce half capacity, then fourth capacity after that, then eighth after that, and so forth.
So if the planet have 1 mining region, and 3 undeveloped regions, and it is fully populated, then 25% of the people will produce full capacity (15 ores for 15 zero people), 25% will produce half capacity (7.5 for 15 zero people), 25% will produce fourth capacity (3.25 for 15 zero people) and finally 25% will produce eighth capacity (1.625 for 15 zero people), for total of 27.375 ores. If you build a second mining region, it will drastically improve the output. It will now have 50% of zero people producing full capacity (30 ores for 30 zero people, already surpassing the one mining region's capacity with full population), and the last 50% producing half capacity (15 ores for 30 zero people), for total of 45 ores, which is about the twice amount of output if you had only one mining region! If 3 regions are mining, the total output will be 52.5. If all 4 regions are mining, then the total output will be 60 ores. The side effect is that there's also diminishing return on developing more regions to be of the same output, to encourage diversity! Is it worth building that last mining region for 7.5 more ores, or to build a research region?
The game will handle spaces automatically, so you just assign your races to whatever output you want them to be in. There won't be a hard limit to a output's capacity, so if you need extra food in an emergency, you can assign more people to food production, but it won't be as effective as actually building a farming region.
This will reduce the micromanagement a lot, and resolves the UI issues with different population limit! You can still build improvements for different regions. The output will be averaged between the regions with the same type of output. If a region produces 2 ores per unit of population, and another only 1 ores, assigning 10 to mining will result in 15 ores ((10 * 2 + 10 * 1) / (2 regions)), so there's incentive to improve all of your regions!
This will be how the population allocation work. The output allocation (like the one in MoO 1) will not apply diminishing returns.
Another note, the region development will be based on the population number, due to several reasons. First, there won't be any sliders on an undeveloped planet (no developed regions), so how to allocate the "production" of the population? Second, it makes sense that the more people you have, the faster a region will develop. So the "cost" for a region will be the "manpower". An example, if a mining region requires "50" manpower, and the planet has 10 people, it will take 5 turns to build that region (5*10). Different regions may have different amount of manpower requirement (research will require a lot more manpower than a farming for example). So even if you're a rich and powerful empire, you can't just "buy" a region, so the best way to do that is to transport people to that planet!
Last several notes, there won't be any regional specials, since it will clutter the UI and overwhelm the player, so there will be planetary specials only.
Each region type will be a technology, with the Mining, Research, Industry, Agriculture, and Commerce being the starting region types (level 0), and there will be different region types in the future to exploit different materials. For example, if a planet has Radioactives, you can't mine those until you research Radioactive Mining/Purification region, then you'll have to sacrifice one or more regions to be devoted entirely to this output. Then you can easily manage the planet output from the planet list screen.
Alright, I think this covers all of the region/planet economy design! Once this concept is implemented, I will attempt to publish the new version on Desura!