Source for the Quick-and-Dirty RPG by N. Phillip Cole
From the rules:
“Quad RPG” means “Quick and Dirty Role-playing Game.” This simple RPG is designed to be picked up and played with not even a moment’s notice and only a modicum of necessary rules-checking. All you need is a mechanism for generating a set of random numbers (dice and cards are common), maybe a handful of pennies or just a notepad to mark some tallies, and this two-sided page (and hopefully if I’ve done my job well enough, you won’t even need that after a good read-through). Pen and paper can also be quite useful.
That’s really all there is to it. Quad is a simple RPG that fits on the front and back of a single sheet of paper. It’s designed to be picked up and played immediately, and serve as a nearly-invisible foundation for games of just about any theme and genre. It was initially released to the crowds at Dragoncon 2008, and as of May 2016 it has been cleaned up and is now available as a free github download.