Creating an empty file named ".nomedia" inside a folder with any media files (audio, image, video) tells to the Android media apps (Gallery, Video Player, Music Player) to ignore that folder.
https://fileinfo.com/extension/nomedia
It's hard to create/copy a .nomedia file using the Android itself, because you can't see (and copy) it in most file managers.
Every time i need to install a new copy of the game i have to use my Windows PC to extract, create the .nomedia files and copy to my android tablet. I tried other ways, but Windows Explorer spends 20 minutes just to index files and allow me to open the images folder for example.
In short: I only spend close to an hour creating these files inside each folder with media files (images, v11, v12).
I hope you understand, english is not my native language.