C.O.R.E. Basic Rules - The Chupa Open Roleplaying Engine

From the introduction:

C.O.R.E. focuses on drama and speed of play. Your character’s skills and abilities, and your vivid imagination, rather than his equipment, determine his capabilities. Instead of focusing on providing rules to cover every aspect of a character’s life, these rules are meant as guidelines, and are an aid to multi-player story construction. Instead of the Director being left to referee every detail, the players are encouraged to take an active part in the story and, hopefully, enjoy a richer story because of it.