"The Buffy the Vampire Slayer and Angel Role-playing Games are complementary, officially licensed role-playing games (RPGs) published by Eden Studios, Inc. The Buffy the Vampire Slayer Core Rulebook was published in 2002, while the Angel Corebook followed in 2003. Both games use a streamlined (or Cinematic) version of Eden Studios' popular Unisystem game engine, also featured in CJ Carella's WitchCraft and All Flesh Must Be Eaten, two of Eden's better-known original product lines. In both games, players are able to take on the roles of characters from the respective television series or create wholly original characters as they and their group see fit, effectively building their own Buffyverse series in the process.
Source: Wikipedia, "Buffy_the_Vampire_Slayer_(role-playing_game)", available under the CC-BY-SA License.