Let's get started:

1. Download and install CRP-Extractor[github.com] (v0.2)
   Original post by Tailgunner on Simtropolis[community.simtropolis.com]
   
2. Visit the workshop and subscribe to the map themes and textures you want to use.

Create a new folder on your computer to save all the different files in. Search in your local Steam folder the map themes you want to use. Workshop files are stored locally, usually in this folder:
Use the search bar. The filename has a .crp-extension. Right click on the file, select copy and paste it into your new created folder.


Start CRP-Extractor and select the files you’ve pasted into the created folder. For each file, create a new output folder to save the files in. Be patient! It could take a moment to extract the files!



After extracting you have all the textures you need and a structure like this:


Example (folder)
- MapTheme1 (folder with output files)
- MapTheme2 (folder with output files)
MapTheme1.crp
MapTheme2.crp

Example of the output folders:

It's time to mix the different textures you want to use in your new map theme. Again, create a new subfolder, for example NewMapTheme.

1. Open the output folder of the map theme you want to use as base theme and copy all the output files into the new created folder NewMapTheme.
   
2. Now pick the textures you want to use from other map themes and copy them into the same folder. For example: if you want to replace the grass texture, copy the grass texture and replace it. Select Copy > Go to folder NewMapTheme > Paste > Replace? > Yes.
   
3. Now you have all the right textures you want to use for your new map theme in one folder. Select all the files and copy them to this local folder:

Before you start creating your own map theme, you need to take a close look at all the settings of the different textures you want to use (Diffuse Tiling). You need to open the original map theme in the Theme Editor and write down the correct texture settings.

1. Start Cities: Skylines.
   
2. Select ‘Load’ and open the map theme with Theme Editor.
   
3. Write down the texture settings you want to use in your custom map theme.
   In this example Grass 0.0200 and Sand 0.0200.
   
4. Close the theme if you are done.

Finally, it's time to create your custom map theme. You have 2 options:

• Use an existing map theme with textures and settings as base theme and change some textures manually (recommended) or,
  
• Create a theme from scratch (definitely something for advanced players).
  If you create a new theme, make sure you select the correct type of the map (Temperate, Boreal, etc) corresponding to the map you want to use. If not, you need Environment Changer to let it work.

For example, I use an existing theme as base and change the grass and sand texture manually.

1. Select ‘Load’ to load an existing map theme with textures and settings as base theme.
   
2. To change the grass and sand textures manually, click on the texture. A new window (Select Texture) will open.
   
3. Select the grass texture in the list. You already copied all the textures you want to use to this folder. If not, please check §1: Unpack textures with CRP-Extractor.

After applying the new texture, make sure to check the Diffuse Tilling-settings of the new texture (0.0200 in this example). Edit the value to the original value you've written down. Repeat the last steps for other textures you want to change.

Save the new map theme and you're done!
Next time you load your city, select the map theme you've created.

If you want more information about creating your own map theme, check out these awesome guide by hadece: Map Themes: In-Depth Guide Terrain.


Feedback, suggestions, tips, tricks? Please let me know in the commands below.