MEGApack update.

I don't understand what you're talking about.

Adding a third tier of creature upgrades to a Castle is a bad idea because it makes it difficult to remove the upgrade information from the creature file when you want to replace a city's creatures with creatures from a mod, right?
First, how is the concept of a third tier of upgrades in a Castle related to what you're writing?
Second, what's so difficult about extracting a single creature from a mod? What kind of "hassle" are you talking about? Unless there's a mess in the files created by some mod authors. But what kind of "HASSLE" is there if the connection between one file and another is easily traceable and it's easy to extract all the necessary files for a specific creature? And mechanically removing upgrades from a creature is simply deleting two lines in a text file. What's the hassle?
And how does this relate to the conversation about a third tier of upgrades in a Castle? I don't understand.

Regarding neutral creature upgrades. If I understand correctly, the argument is that "it's bad because it weakens the original neutral creatures." If I understand correctly, the idea is that stronger and less "balanced" creatures appear. I don't know, maybe there's some merit to that. But in any case, it's solvable. You can make them not upgrades, but basic creatures. You can give the characteristics of basic creatures to the upgrades and weaken the original. There are solutions to the problem, so I still don't understand such a categorical rejection of neutral creature upgrades.

Or is the point that when creating new creatures, you shouldn't create weaker versions of existing creatures? I really don't understand. And why shouldn't you? What's wrong with a weak and a strong version of the same creature?

And about the 2k creatures. Is it worth it? What's the point of having such a large number of neutral creatures? And, if I understand your idea correctly, these will be neutral creatures that are not available from Castles, encountered on maps, and... without upgrades. Or are you saying that only neutral creatures from the base game "shouldn't" have upgrades?
In the end, there will be TWO THOUSAND creatures, and the player will see at most only a hundred or so. I don't understand. Why? Besides, do we really have 2k gameplay-interesting creatures, with good balance, that look interesting, good, and high-quality? Wouldn't it be better to make fewer, but... better?

Added 5 minutes later

I don't need them at all, and this "spinner" in the city is just so-so. I don't even like that neutral creatures have upgrades; they shouldn't have them at all.

But nothing has been released yet, neither new files for the 2k creatures nor the creatures themselves.

"Spinner in the city" still puts me in a stupor. What is that?