The Mongoose Pocket Player's Handbook

From the back cover:
"The Mongoose Pocket Player's Handbook is a simple guide to the world's most popular roleplaying game system. It contains exactly what a reader needs to play the game and nothing else.

With this guide to the intricacies of the OGL rules set, Players and Games Masters can make use of any other setting material or devise their own for a campaign that is uniquely theirs while still retaining the basic framework of the OGL game. If it is a basic rule covering character creation, combat, equipment or magic, it has a home in these pages.

Everything you need, in a pocket-sized edition with a pocket-sized price."