UHC.zip is a release file of the Minecraft map Ultimate Hard Core, made for Minecraft 1.11, 1.11.1, 1.11.2. It was published on February 17, 2017 and is 2.9 MB in size. For the full description, screenshots and every other version, visit the Ultimate Hard Core map page.
How to install: Extract the .zip and move the world folder into .minecraft/saves; the map then appears in your Singleplayer list.