This theme is based loosely off of the Gloom theme for TextMate and Sublime Text. It is optimized for heavy use of the .todo mode, with lots of useful tags.
In order to install this theme (as of FoldingText v1.2.2), the User.fttheme folder needs to be placed into ~/Library/Containers/com.foldingtext.FoldingText/Data/Library/Application Support/FoldingText/Themes/.
This theme uses the Powerline-optimized version of Adobe's free Source Code Pro font. It can be obtained from the powerline-fonts repository. If you wish to use another font, just replace any instances of 'SauceCodePowerline-Medium' in the style.css file with the name of the font you wish to use.