The Call of Cthulhu d20 Core Rulebook, published by Wizards of the Coast in 2002, represents a unique fusion of the world's most popular tabletop engine with the definitive cosmic horror setting. Designed by gaming veterans Monte Cook and John Tynes, it was created during the height of the d20 system's "Open Game License" (OGL) era, aiming to bridge the gap between high-fantasy heroics and the bleak, investigative horror of H.P. Lovecraft’s mythos. A Radical Mechanical Departure
: Borrowed from Chaosium’s original version, this mechanic tracks the mental erosion of investigators. As characters encounter cosmic truths, they risk temporary or permanent madness, emphasizing that knowledge is more dangerous than physical wounds. Call of Cthulhu - D20 Core
: The system adapts classic feats for a modern or 1920s setting—transforming "Ride-By Attack" into "Drive-By Attack"—while prioritizing investigative skills over pure combat prowess. Bridging Two Worlds The Call of Cthulhu d20 Core Rulebook, published