I suspect if the build priority is lowered below that of the matching factory or lab that the AI simply would not ever build these.
I have set the value for factories to 10 and the value for the production enhancers on 5, and the AI keeps building the enhancers. Sometimes, it will build them even without any factories, though, as far as I can tell, it does that mostly on planets it conquered or flipped.
The Drengin/Korath improvements I think could do with some streamlining, perhaps upgrade paths so the structures improve rather than just getting more of them.
I changed them this way: Devil's Forge (+20% manu bonus, 125 cost) gets upgraded to Slaveling Training Center (+30%, 185), which gets upgraded to Artificial Slaveling Pods (+40%, 245). The Korath can upgrade the Death Furnace (+30%, 150) to Wretched Harvester (+40%, 225), while the Aul Incinerator (+30%, 300) stays independent. The maintenance for all is 5bc, except for the Aul Incinerator. PQ -1 is maintenance enough for it.
I changed the tech requirement for Wretched Cloning to Death Furnace to keep the industrial techs all in one spot. While Xeno Medicine makes sense as tech requirement, I really think that this change is for the better. I could change the requirement to both techs, but that would look horrible and I'm not sure how the AI would handle this.
Additionally, I added the Agony Coordination Grid (+40% research bonus, 150 cost) improvement, because the tech makes mention of it. It is an upgrade for the Pain Amplifiers (+20%, 100). The maintenance stays at 4bc.
I tackled the problem of +% structures for v3.1. Each now has a base production proportional to its +%, and costs/maintenance have been brought down so the AI doesn't get stuck spending a year to put up a power plant or research coordination center.
While I understand the reason behind this, I'm a bit worried about how the AI will handle this change. A base MP/RP value will increase the chance that the AI will build the production enhancers on a bonus tile. If the value is too low compared to a regular factory/lab, could this greatly hamper the production output for the AI compared to the player. On the other hand, if the value is the same as a comparative factory/lab, would this make the production enhancers overpowered compared to SPs. Do you have tested those changes yet? I really hope, that my worries are unnecessary.
Actually, with all the work I've done making the Drengin and Korath similar, I need to go back and see what makes them distinct. The Korath have a number of powerful techs that the Drengin lack, so what do the Drengin get that makes it worth using their TechTree instead? Things like fleet modules and planetary defense were Drengin-only, but now I've made them universal.
Thanks for reminding me. The same is true in my mod. The Korath are better than the Drengin in every way. Gotta find something, that makes the Drengin worth choosing over their cousins.
For morale structures, I've been considering making them one-per-planet, but more powerful.
I mentioned earlier, that I considered doing this, too. I have seen plenty of cases were the AI has a decent approval overall, that is made up of a few planets with very good approval, and several more planets with approval in the reds and a constant loss of population. To decide how big the morale bonus should be, I therefore needed to know how big the max population will be. In other words, I had to finally find a solution of how to make farms balanced 1pp-improvements.
The biggest problems in doing that was the difference in population limit of the homeworld (16b) and colonies (8b), and the bonus tiles. Farm sizes, that would work good on a colony, don't work on the homeworld. And the bonus tiles would throw any balancing out of the window. In the end, I decided to make the pop limit for both homeworld and colonies the same (12b) and lowered the max bonus from farms to 3mt. I also changed the Yor Charging Stalk to give a +%-bonus instead of a fixed value, because they needed the biggest population, but bonus tiles (again) would make any balancing impossible. It also doesn't make sense, that fertile soil increases the energy output of the Stalks.
Testing this change was difficult, due to my ongoing hardware problems, and disappointing, because the AI refused to build any farms on their planets, despite a very high AI value. Only the Yor built their Charging Stalks, but I believe, that this had more to do with the morale bonus. My guess is, that the AI thought that a population of 12b is enough. I also noticed something interesting: food fractions get rounded down (e.g. a food bonus of 0.8mt gets rounded down to 0mt).
For my next test, I reduced the base pop limit to 8b. The result was, that those races, that didn't start out with a farming improvement, had later only rarely enough space to build a farm. So, I decided to add a basic farm improvement. Balancing was again quite difficult, due to the bonus tiles, so I changed all farms to provide a +%-bonus instead of a fixed value. This makes the bonus tiles worthless, but, I think, it is for the best. The current values are:
Basic Farm (+15% food bonus, 20 cost)
Xeno Farm (+25%, 30)
Enhanced Xeno Farm (+50%, 40)
Advanced Xeno Farm (+75%, 50)
Robotic Farm (+75%, 50)
Harvester (+25%, +5% pop-growth, 20, no longer indestructible)
Basic Stalks (+25%, +25% morale, 25)
Charging Stalks (+50%, +50%, 35)
Advanced Charging Stalks (+150%, +150%, 45)
All farms have a maintenance of 1bc, except Harvester, which has none. Food Distribution Center and Fertility Clinic got sacked. As you can see, the max pop limit will be 20b for the Yor, 16b for the Torians, 15b for the Arceans (see later) and 14b for the rest. The Thalans can have a bigger pop limit on up to two of their planets, due to the Hyperion Matrix (+75% food bonus) and the Gaia Vortex (+15%), but don't have access to the Basic Farm at the start. Neither do the Drengin, Korath and Torians. The Torians start with the more powerful Harvester, so they won't need it. The Drengin and Korath, on the other hand, sure do. Basic Farm currently has Industrial Revolution as tech requirement. I'm a bit weary of adding yet another starting tech to the game (already did Capitalism, Traditional Entertainment and Traditional Temples). Giving the Drengin/Korath unique farming improvements (with the same or similar values) and techs, will probably be the best solution.
I still need to go after the morale improvements, but that is out of the question for now. My latest test lead to a freeze-up of the system. A stability test later crashed it (the PC shutdown completely). So much for my hope, that the RAM would be the culprit.
In any case, two more changes I made:
The Krynn have now access to Traditional Temples (but not the upgrade to Drathian Temples), because Entertainment Networks make absolutely no sense for them.
I also had another look at the Biosphere Modulator and Weather Control Zenith, and finally discovered what always bothered me about them. Why has the Modulator a manufacturing bonus? It doesn't really makes sense. The Modulator makes "the planet adapt to us", as the description says. So, why not a bonus to pop-growth? And why has the Weather Control Zenith no additional bonus? If there is one area, that should see a boost due to weather control, it is farming. So, the values are now:
Biosphere Modulator (+3PQ, +10% pop-growth, 60 cost)
Weather Control Zenith (+3PQ, +15% food bonus, 60)
The maintenance for each is 2bc.
Enough for now. I have to find out what I need to replace as soon as I have enough money.