You may never heard of Candra OS because the distribution is fairly new in the world of Linux, in fact their isn't stable release yet, but killhellokitty added their OS default theme to the gallery. Candra OS themes are flat and minimalist, it offers light and dark version of GTK themes, also includes two themes for Gnome shell. Basically these themes are intended to use in Gnome Shell 3.16, Xfce, Lxde, Cinnamon & Openbox, but you can also use Gnome Shell and GTK with 3.14 version as we tested, it doesn't work properly under Unity desktop. Well there isn't much information about themes and OS yet but you can install and try. If you are using other distribution you can directly download theme and install it manually. Amiga OSX icons used in following screenshots. You can use Gnome-tweak-tool to change icons/themes.
To install Candra OS Themes in Ubuntu 15.04 Vivid/15.10 Wily/14.04 Trusty/Linux Mint 17.x/17/other related Ubuntu based distributions open Terminal and copy the following commands in the Terminal:
What do you say about these themes?