I had GOG Skyrim installed and the mod appeared in my game library. Is that based on Skyrim being installed or just having it listed in my game library?

Will the mod game install and function without Skyrim being installed?

What is the name of this 'mod'?

Enderal: Forgotten Stories

Thats is not a 'mod'. Its a standalone total conversion thats been posted about several times here already.

Its not recommended to install it until you have finished Skyrim cause it might mess up the game.