This theme is exactly the one that Google put in Android N preview, extended on more appsm and with Pixel accent color. CyanogenMod/CyanogenOS ROM is needed If you don't have it, do not buy the theme.
Piereligio is the developer of the app that can be found in the Personalization category. Over 0,5K users downloaded and set up O/Pixel Dark theme Mode CM13 and the most recent release was on May 7, 2017. Users rated this application 4.5 on Google Play.
You are able to get the installation package of O/Pixel Dark theme Mode CM13 134 free of charge and have a look at users' reviews on Droid Informer. The app works fine on Android 5.0 and above. It's secure to download the app.
Users leave reviews pointing out that you can get such benefits of this application as constant updates and great support.