[question] Empty Lot? I wanna use it...

I believe you can accomplish this deed... first you would have to make the lots buildable. Then you would set the terrain to build this lots to the appropriate lots to build buildings. That is land, forest, hills, etc. Then you would have to set every other improvements preferred terrain to not be allowed to be built on anything except city. Not sure why you would want to do this, but that would be the way to go about it.

One more question: I am stumped about outposts/arcane monolith, I want to make some new additions of my own and I can't find the code that binds the outpost improvement to the outpost itself.

I want to make a different outpost with it's own build options, rather than the ones already present.

To give a small hint about lots:

It is the first step of a small project I want to do. The lots might sound whacky up front, however a lot can be done with them. I will give each city a maximum number of lots, and upgrading cityhubs will increase the lots you may place (thus, buildings you may have).

To balance this, I am making an outpost called "Small Town" which will be placed by a spell that costs gold and population. Some improvements will be moved from the city to the "Small Town".  Lots for the cities (with reduced building options) will redesign how cities grow.

I also looked at the Burning Tiles mod, and am thinking about asking permission to create a "desecrate land" variant for it, because it fits into what I want to do.

Well after experimenting for awhile, it doesn't seem possible to build an empty lot. Although I don't understand why.

I am going to need to create a building with no function and the "empty lot" art tags...

But you will not be able to build on top of that improvement. You can improve over the spot, but you need to tell what it will morph to, not sure if you can put multiple tags here, but let me know if you are successful. Otherwise, you might develop a resource that you get a certain amount when you settle a city and it costs you 1 of these resources to build an improvement. But I'm not sure if the AI can handle what you are about to do here.

that is the other issue i am trying to work out; the best option is that when the "upgrade" is selected and work begins, the improvement for empty lot is remove and replaced.

I could also make 2-3 different types of lots to help the AI prioritize itself correctly.

Every building I create that references empty lot art tags doesn't even show up, I wonder if there is something internal i don't know about interfering.

I wonder if I can copy the art def's of Empty Lot, change the names of some files (to prevent internal mechanisms from recognizing them) and proceed as normal. I have tried several means to "force" the empty lot and its smarter than me for the time being.

Now I need to figure out my limits of making different outpost types which have only their own improvements and not improvements of other types of outposts.

That was the problem I was having with it earlier. I had no problem making buildings before and setting particular properties with these buildings. I do think that the empty lot has some special internal commands that we don't know about (specifically around the art definitions).