Sadness
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Of course, such underground areas on a small map are pleasing, and after this, games don't look so bad when played on high settings instead of low ones.
This has nothing to do with the functionality of Fresh Mod. The sizes of zones are determined by the template, in the "base size" column in rmg.txt.
Here is this link where you can download a program for editing templates and experiment with it; perhaps you will gain some insights. P.S. The standard Windows archiver cannot open it; I was only able to use 7zip