Arrival_of_Darkness_16x_v_1.7.zip is a release file of the Minecraft resource pack Arrival of Darkness 16x. It was published on June 13, 2012 and is 4.6 MB in size. For the full description, screenshots and every other version, visit the Arrival of Darkness 16x resource pack page.
How to install: Put the .zip into .minecraft/resourcepacks (do not extract it) and enable it under Options → Resource Packs.