Nix_Parkour_11_Challenges.zip is a release file of the Minecraft map Nix Parkour: 11 Challenges, made for Minecraft 1.7.4. It was published on December 24, 2013 and is 5.1 MB in size. For the full description, screenshots and every other version, visit the Nix Parkour: 11 Challenges map page.
How to install: Extract the .zip and move the world folder into .minecraft/saves; the map then appears in your Singleplayer list.