From wikipedia , "Call of Cthulhu is a horror fiction role-playing game based on H. P. Lovecraft's story of the same name and the associated Cthulhu Mythos. The game, often abbreviated as CoC, is published by Chaosium; it was first released in 1981 and is currently in its seventh edition, with many different versions released. It makes use of Chaosium's Basic Role-Playing (BRP) system, with special rules for Sanity."
Add the Scooby Doo cast and the horror just grows! Episode 10 was a Scooby Doo-run Call of Cthulhu!