This is a script I wrote that I use in conjunction with cron to periodically change my desktop theme, so it doesn't become too boring.
I'll post it here together with the color scheme files and wallpaper images, in case someone wants to use it.

Here is the script:
http://ix.io/1cDM

Here are the color schemes:
http://ix.io/1cDH

The color schemes are taken from various internet sources, especially from xero (https://github.com/xero).

And here are the exact wallpapers I use:
https://imgur.com/a/NSTbGcZ

I will post screenshots of each theme in the thread.