Puzzles are difficult.
Game is non-linear.
It is a foggy day in modern day San Francisco. You are lost, when suddenly a stranger appears and alludes to an ancient dangerous mystery that most have forgotten but a few are still trying to search out. You are outside the house of one of the most recent researchers. You do, of course, start to research this ancient mystery yourself. You go can go into this house or one of a number of other San Francisco sites.