This is just a naked character creation packet. It explains how to create a level 1 character and get rolling on the day of the game, but absolutely nothing else. It is assumed that the DM is a badass who can explain the other rules on the fly. This document also hopes to explain a couple of the distinctions that trip up new players (like ability score vs ability bonus).
The rules are shamefully minimal adaptation of an already-minimal game, but it's not so barebones that these characters couldn't easily plug into other retroclones.