2000 · ソースブック（プレイを拡張するルール／オプション）
The Keeper's Companion
A reference supplement for running Call of Cthulhu games, covering investigative guidance, occult knowledge, and Mythos lore. It includes advice for Keepers, summaries of more than 60 occult books, historical languages and scripts, arcane artifacts, secret cults, forensic medicine, alien races, and mysterious locations. Additional material covers skill applications, alternate rules, resistance tables, law-enforcement timelines, causes of death, investigator sheets, and other tools for scenario preparation. Revised chapters on forbidden books, secret cults, alien races, and mysterious places are included.
- プレイ人数
- 0
属性／ステータス制（STR、CON、PERなど）ランダム属性生成（キャラクター作成時）スキルベース（スキルを購入または獲得）
ゲーム情報（人数、プレイ時間、対象年齢、クレジット）の出典：BoardGameGeek。