you can find information here:
http://forum.df2.ru/index.php?showforum=79you will need: 1. knowledge of the def and psx formats, and programs for working with them, or someone with these skills.
2. the ability to work with 2D graphics (city background and processing backgrounds for buildings, creatures, portraits, etc.), using software like Photoshop, or someone with these skills.
3. a 3D modeler - for creating creatures and buildings, with animation and texturing, and importing all of this into frames for subsequent conversion according to point 1.
4. a sound designer to create creature sounds, and either a composer or the same sound designer to create the city theme.
5. a modder who can edit resources to change characteristics/properties and integrate everything you've created into the game (if you're just replacing a city, there isn't much work involved).
All of the above is only necessary for REPLACING a city, i.e., removing one city from everywhere and simply inserting yours in its place, and if you need to make changes to various characteristics.
To add a new city to the game, you need... excellent reverse engineering skills, assembly language skills, or at least basic coding skills with knowledge of hooks.
New cities are already being integrated into the game, but for the past 5 years, this has been done by very large teams, and only two have succeeded, but their product is still not fully developed and may not be finalized for another year.
My advice is to join one of the teams... it will be easier... if you want to do it on your own, you will need everything listed above.
I understand that game development is a wonderful dream, but without serious and persistent work, it will remain just a dream