The Basic Roleplaying System is one of the oldest and most beloved systems in RPG history. It has been around since 1980 and has powered games from RuneQuest (1st & 2nd Editions) and Call of Cthulhu to Stormbringer and (in modified form) Pendragon (1st - 5th Editions). Though many gamers have problems with aspects of the system, it is generally well regarded as being a simple, intuitive, and playable game.
Basic Roleplaying: The Chaosium System, intended to be an introductory RPG, tries to simplify an already simple system, and does so by removing the vast majority of what actually makes the game run. The game uses standard Chaosium attributes (Strength, Constitution, Size, Intelligence, Power, Dexterity, and Appearance), but only has 8 skills: Climb, First Aid, Hide, Jump, Listen, Sneak, Spot Hidden, and Throw. The game mentions other skills, but never gives rules, stats, or any information about them – other than that they are sometimes necessary and can be found in other games. Weapon skills are all based on the type of weapon being used, with everyone starting with the same skill for the same weapon, and everyone doing the same damage with the same weapon. Once again things like alternate weapons and multiple types of armor are mentioned, but no stats are given for them. Similarly the classic Idea and Luck rolls are present, but with incomplete and contradictory rules given for their implementation.