From the introductory notes:
Welcome to Locket Away, a solo adventure using the Unbelievably Simple Role Playing system(available for free!) devised by Scott Malthouse.
This adventure is designed for a starting character who is a hard boiled investigator in the dangerous and unpredictable fantasy city of Jailton. This will serve as an introduction to the USR rules.
This PDF solitaire adventure has clickable links for the numbered paragraph choices throughout.