Theme Bootswatch is child theme for Bootstrap3. It is build using the bootswatches created by Tomas Park (http://bootswatch.com)
Bootswatches are usually made from 2 files. One bootwatch.less file and one variables.less file. You can easily create your own bootswatch modifying one of these files or creating new ones yourself.
The benefit of Bootswatches is that you will probably not break anything in your theme when styling it using your fonts colours and sizing.
This is a Moodle 2.7 and newer theme only. It relies on Moodle creating css files form the Bootstrap, Moodle and Bootswatch less files.
After installing this theme go to your Bootswatch theme settings page and try your favorite Bootswatch.
If you find any bugs or issue, please us the Github page for this theme: https://github.com/bmbrands/moodle-theme_bootswatch.