Neptune is a GNU/Linux distribution based on Debian stable branch. Currently, it is based on Debian 9.x stretch. Neptune ships all packages from the Debian repositories except for Linux Kernel and some additional drivers. It provides a recent version of Linux Kernel and drivers for better hardware compatibility.
The main aim of Neptune is delivering an elegant, out of the box desktop experience. Towards this goal, Neptune ships a simplified plasma desktop with a set of multimedia codecs, flash player, audio and video players.
Most of the packages in Neptune is inherited from Debian repositories itself. It also makes use of packages from Netrunner. Neptune also maintains their own repository to package some of the custom applications.