Basic Roleplaying is the core roleplaying game system used by the small publishing company Chaosium, Inc. It's a simple, intuitive system, with no classes or levels. The game system has been used for RuneQuest, Stormbringer, ElfQuest, Worlds of Wonder, Nephilim, Call of Cthulhu, and many other roleplaying systems. Chaosium is now releasing their Basic Roleplaying system again, as a generic d100 roleplaying system - capable of running anything from fantasy to sci-fi to superhero games.