Inverse of the typical RPG - you are the Guardian.
Your system may require the command from within the nothack directory:
python ./nothack
Python 2.7 and PyGame (test on version 1.9.1) can be installed with:
sudo apt-get install python2.7 python-pygame
Credit for the original code base of NotHack to Roger 'Denor' Ostrander, 2002, for the Ludum Dare 48 Hour Contest #1.