Call of Cthulhu 7th Ed: Alone Against the Flames - Rules of Play says:
This is a solo adventure for the Call of Cthulhu game. It is a horror story set in the 1920s where you are the main character, and your choices determine the outcome. It is also designed to lead you through the basic rules of the game in a gradual and entertaining fashion. Although most such adventures are played with your friends, this one is just for you.