Darko is an icon pack. It is not a stand alone application you need a third party launcher to apply it.

Darko: A dark set with shadow for depth. Use it with any dark wallpaper for better depth effect.

What's included:

★ 3.000 + HD icons (256x256)
★ 40+ matching HD cloud wallpapers!
★ Launchers support: Action Adw AdwEX Apex Atom Aviate GO NextNova Smart Solo...
★ Icon masking for un-themed icons
★ Dynamic calendar (For Nova Launcher)
★ Alternative icons to choose
★ Updates.