Basic Roleplaying: Universal Game Engine

Basic Roleplaying, or BRP, is a generic, universal system for tabletop roleplaying games used primarily by the publisher Chaosium for its flagship games, most notably Call of Cthulhu and RuneQuest. At its core, Basic Roleplaying is a skill-based percentile system, meaning players roll a d100, trying to roll under their skill level, which is rated from 0-100%, depending on how skilled the character is in a given area. Characters in BRP have seven stats: Strength, Constitution, Size, Intelligence, Dexterity, Power, and Appearance. They have several other characteristics derived from these, but more importantly, they have skills. What skills are available depend on the setting and theme of the campaign (you might see Library Use and Psychotherapy in Call of Cthulhu, for example, or Energy Weapon and Astronomy in a sci-fi game). These skills have ratings that determine how likely the character is to succeed at the average task in that field, expressed as a percentage. When players roll to use a skill, they roll two d10s to simulate a 100-sided die and aim to roll below their skill level. For a particularly difficult challenge, they might need to roll below half their skill level. Generally, lower rolls are better in BRP! Some versions of BRP also allow players to "push" failed rolls to try again, with the caveat that consequences will be worse if they fail a second time. Characters can occasionally improve their skills by using them, but higher skills are more difficult to raise than lower ones. A campaign can strike a more realistic tone with skill levels generally under 70-80%, or a heroic or even superheroic tone with skill levels up to 100% and above. There are also optional modules for magic and the occult. BRP is probably best known in Call of Cthulhu, Chaosium's most popular tabletop RPG, but it's been used in fantasy, science fiction, and superhero games as well.