As you may know, Variety is an app indicator that changes the desktop wallpaper, using automatically downloaded images from: Wallhaven.cc, Flickr, Wallpapers.net, Desktoppr, NASA Astronomy Picture of the Day.
It works well on the most popular desktop environments: Unity, Gnome Shell, KDE, XFCE, LXDE, Enlightenment, Cinnamon, Mate and Pantheon.
The latest version available is Variety 0.6.0, which is the first version of the software that includes a slideshow feature.
Up to date packages are available via the developer’s PPA, so installing the software on Ubuntu systems is easy. Add the PPA to your system, update the local repository index and install the variety package:
$ sudo add-apt-repository ppa:peterlevi/ppa
$ sudo apt-get update
$ sudo apt-get install variety variety-slideshow
Optional, to remove variety, do:
$ sudo apt-get remove variety
The installation instructions should work on Ubuntu 16.04 Xenial Xerus, Ubuntu 15.10 Wily Werewolf, Ubuntu 14.04 Trusty Tahr, Linux Mint 17.x, Elementary OS 0.3 Freya and other Ubuntu derivative systems.