Parts Per Million has released a new solitaire Mythos roleplaying game in print and PDF. Rogue Handler is set in the modern day and provides mission and clue generation which you can use other published adventures with as well. The 46 page book is available in softcover, with PDF, for $13.99 on in PDF alone for $4.95 at DriveThruRPG.
About the book:
Solo Roleplaying in a World of Conspiracy and Cosmic Horror
This supplement makes solo roleplaying most d100 Modern Setting Cthulhu Mythos games a real possibility. These rules add a simple yes-no oracle, for answering questions, along with a set of guidelines for evolving mysteries to be solved as you play. This as-you-play method means that you will not know what is going on until your Agent learns the truth for themselves.
In addition to the oracle and mission generators, these rules add countdown clocks to add tension to your scenes and uses any sourcebooks, rulebooks, or fiction that you want to use as a source of clues, flavor content, and to answer questions that do not fit into a yes-no format or are not covered by the tables provided. You roll for a random page (d100), then paragraph (d6), and then sentence (d6), do that a couple of times, and then pick out the words that seem to fit your situation, and play style.