Description from the publisher:
Cornerstone is a light, universal, RPG system toolkit. It is my answer to Freeform Universal, Fate, GURPS, and Savage Worlds. The game is 1d6, works with nearly any genre, and allows for quick setup and play.
•Easy to play and run
•1d6 core mechanic
•Every roll generates interesting results
•No metacurrency or narrative points
•Scalable to fit broad or focused game concepts
This is the basic edition, which is a cut down and simplified version of Cornerstone (to be released in the future), without as much advice or as many examples given. But, best of all, it is absolutely free, and contains everything you need to play an impromptu gaming session in your favorite setting.