NCF – Extended list of Neutral creatures.

I installed Visual Studio, but when I run it, it displays something about an entry point in the procedure... Does this program have no problems running, or does it require some complicated steps?

The program has no problems running; the problem is a lack of components (if the required programming language is not in the components, it will display gibberish).
You can also try copying the executable to a separate folder, right-clicking on it, and selecting "Open with" so that it doesn't pull in unnecessary files (otherwise, it starts opening as a project).

Added 4 minutes later

Thank you for the informative answer. Can a new city and faction be added in this way?

To add a new city, there are two ways:
1) find the source code
2) modify an existing one by trial and error, but for a new city, you will need:
a) new IDs for creatures, models, and so on
b) the models, creatures, and so on (but this is not a problem)
c) everything listed above must be in the format used by default in the game (there is a small loophole here: if you are going to modify the executable, you can create a module that will read other formats. This will be a big boost for Modding, but I don't know what the situation is regarding copyright and other things (maybe it's legal because it's considered a mod, or maybe not because the executable has been copied and modified))