Gumshoe is a family of mystery RPGs and they've come out with a spin off system Gumshoe one-2-one for a single player and GM. There isn't a base book for the sy

Gumshoe is a family of mystery RPGs and they've come out with a spin off system Gumshoe one-2-one for a single player and GM. There isn't a base book for the system but specific ones for Cthulhu, sci fi, teen detectives etc. Ironsworn and it's sci fi spin off Starforged also work well one on one.