Correct, I felt the range you initially set up was too restrictive to really do much within.
I hadn't considered that, hmm, would it not be possible to set AIWeight for the promotions to balance this out? I know that's a crowbar we should avoid using, but...
It's problematic. The code evaluation is currently a little too simplistic as it is and awaiting further adjusting for some new AI's that will be coming soon. Basically, the more a unit has invisibility or visibility of a particular type, the more the unit is drawn to enhance it. It would be tricky to say the least to try to use AIWeight settings given the wide amount of unit AIs and the best selections for those types - AI weight doesn't care about the unit type or status. There's probably still quite a bit of work to get the AI advanced enough here as it stands but made much more complex if we have to make different types of visibility have differing values in their intensities.
I suppose something could be done to make a tag on InvisibleInfos that could create some variation but I do like to keep AI coding simple if I can.
Would not a unit with 16 visibility have 16,15,14,13 visibility for those 4 tiles out?
Yes, and with a wider numeric scale, this would mean that most units end up in an all or nothing category and few would end up being visible to a variated degree. In the above example, anything 13 or less would be fully visible.
The only issue I see is that it is hard to evaluate if a promotion that gives vis.-range would be worth picking as there are some intensity values where additional range would not help as much as with other intensities.
That's an additional point to consider among many yes.
Does vis.-range restrict itself to specific invisibility types?
Yes.
One could just avoid defining promotions that give visibility range to only Invisible_Size.
Range promos are basically 'lesser' intensity promotions since intensity adds a range itself as well as enhancing the cap. Therefore its use is already a little rare and generally applies to units that probably already have a strong visibility intensity or are not supposed to be able to enhance their intensities at the same degree of capability as other units that have access to better abilities to do so.
Would it be possible to get intensity to drop by two point per tile out Invisible_Size, from last example 16,14,12,10?
It would be but then again it's another special reference to the type of invisibility we're talking about and would introduce more mathematical complexity to a segment of code I'm desperately trying to keep as streamlined as possible despite wanting to include these effects. That said, I'll mull on this. At the moment, given the current coding, this is not possible.
I don't think this would be a problem if we change all master hunters to be Divine-Solo so they can see Solo-Diminuative with only Hunting Sight I. If we further made Hunting Instruction building give "HS I" for free to all visiting hunter units this would really not be a problem as only animals are diminuative.
Changing Master hunters to be Divine-Solo is a problem in its own right. Perhaps you've noticed no unit begins with Divine. It's a ground rule to allow for some growth for any unit. It would also further throw their strength out of whack since they're already Solo if I'm not mistaken and you'd have to compensate by making them size small which would be... odd since they aren't midgets.
Only high-tech nanobotstuff is Size_Fine and this could be addressed with special nanobot hunting units.
Also locusts. Future stuff could be addressed with some interesting stuff, yes, and that's the kind of fleshing out the system does truly need.
Some higher, some lower. Tarantulas have exceptional quality while I would rather set them, and the dartfrog, to pathethic quality these are units that should not be able to take actions based on a unit being some kilometers away from it unless it's so many or large a unit that the earth rumbles.
Visibility is obviously only one of many factors that quality works on. Tarantulas, for their size, are actually master hunters and even potential threats to a human being so shouldn't be penalized just to fit them into the visibility scheme better imo.
Actually; this makes me want to ask you if you could make a tag that gives additional vis. intensity only to the tile that the unit is observing from, this would work even better if you manage to create a mission to start battle between two units sharing a tile.
This makes me wonder if the math is a little fuzzy... I might be off by one. And yes, same plot battles are something I'll be working on for my next project. So very soon. As for visibility only to the same plot... I suppose that could be done but we're pushing past the amount of data I wanted the game to spend on this as it is so I'm reluctant unless its absolutely necessary.
Ah, I balanced the numbers thinking of battalion as 108 (solo=1-2, party=4, squad=12, etc.*3 → countless=708588). Anyways, I used a similar reasoning as only incapable→pathetic would be unable to notice a battalion of soldiers. The only difference is that I considered incapable to be reserved for units that doesn't react to their environment like the locust swarm, a plant or a blind-deaf/"too sick to stand upright" being; and I considered pathetic to not be far less common in combatant units than you did, meaning mostly reserved for animals and special cases. Even Inferior should be incredible uncommon in trainable combatants, perhaps only disorganized ruffians or some such.
Don't think we're too far off agreement to an extent. Civilian units are not usually anywhere near standard though. A trained unit of modern Infantry sets the standard for 'standard'.
And when considering, don't just think of the lethality of the unit but the psychological preparedness for combat the unit may have. Most modern humans, even when trained, aren't as savage as they once naturally were. This is why you'll see human units slowly degrade in average combat quality as they develop more technology that makes them individually softer people.
Alertness is related to this in that a high quality unit sees the world as filled with potential threats to be aware of where a low quality unit either doesn't have quite the impression of environmental hostility or the impression that they could do something about it if something hit the fan anyhow. Some unit types are too deeply thoughtful and thus are low quality. Take healers for example. Fear of combat reduces quality as well.
Unless moving in large numbers, any unit in hostile territory would try to hold a natural low profile, and not go waving their banner high and shouting their lords name and profanities about other cultures in their own language.
Is it really a big factor if a newly trained Poor Quality unit is capable of identifying a Squad as a potential threat or a target that should be reported up the chain of command. I consider a Poor unit to basically be some randoms who have been conscripted, given weapons and equipment, and told to risk their life without proper salary, motivation or training.
Probably not an off assessment. Except that I still think it's dangerous to give too much strength to size invisibility. If you do, you'll start seeing players splitting up their stacks to the minimum so as to sneak past the enemy and then remerging them (which isn't something I want to make impossible, just not so obvious that it would work or not.)
Hadn't considered that

, but can't a promotion be defined twize and have ongameoption (or dependency) and visibilitychanges in only 1 of them. Won't their effect only be merged with the game-option on?
Sure but it would need 4 definitions if you wanted to consider:
A) Hide and Seek and Size Matters off
B) Hide and Seek on alone
C) Size Matters on alone
D) Hide and Seek and Size Matters on
(Although you'd only need A and D if it only interacts with size invisibility types so I suppose you could get away with it here. just keep in mind these option edits can be easy to forget they've been defined.)
Remember... Size Invisibility should only be a factor if both are on.
I actually didn't know about the low-profile promoline until now; i might have to reevaluate the excel sheet with that in mind. I just didn't think to check as I thought to myself that no promo could change your size

.
Doesn't change your size but it does represent the unit actually trying to not be seen without using any kind of alternative coloration to blend into the terrain or any special hiding skill.
My thoughts exactly, perhaps a +1 to visibility for each size bigger than colossal and a bigger jump from Size_Diminuative→Size_Fine (1,2,3,4,5,6,7,10).
Something like that perhaps. (I decided on +1 size visibility for units with each size category less than Medium. Should be sufficient unless you're working with your expanded numeric method - which would certainly make for an interesting modmod for players to test the difference.)