This book is designed for use with 7th Edition Call of Cthulhu but will work perfectly well with any edition if you are aware of the positive and negative dice rules and the concept of half and one-fifth values. A character's Luck, half luck, and one-fifth of their Luck attribute play a major role here. I am fully aware that these are not the only solo rules for Call of Cthulhu in the Miskatonic Repository. This book takes a completely different approach to solo play than the Solo Investigators Handbook. -description on drivethrurpg