Eden Studios, Inc. is an American role-playing game publisher founded in 1996, Eden Studios is best known for the Buffyverse role-playing games - 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 what year?