The 21 Steps: A short story written with GoogleMaps

How would you write a story with GoogleMaps? It turns out that Charles Cumming has done it, and it’s very clever. I ended up reading the whole thing: http://wetellstories.co.uk/stories/week1/ The 21 Steps is a real page turner — except there aren’t any pages. Just GoogleMaps bubbles. If you have a chance to read it, let me know what you think of the format.