Oh, Perplex City, you are still much-missed. From 2004 to 2007 I was lead writer on Europe's first Alternate Reality Game of any size or note (what we now call "transmedia").
It was an incredible project, with the kind of cameraderie that's hard to find in any job - we all cared so much about the imaginary city we'd created, and I'm still good friends with the other writers.
In brief, Perplex City had lost its Cube - a mysterious object with mystical powers - and they'd discovered that it was somewhere on Earth. Perplex City exists in another reality, and can only communicate with us through the internet. We can look at some of their internet, they can look at some of ours, and so our Earth players needed to follow the blogs of characters, study accounts of the Cube's theft and lots of other pieces of information about the city to find out who'd taken it, why, and where they'd buried it.
Oh, and if you found it and dug it up and brought it to us, Mind Candy would give you £100,000 - a gift from the grateful people of Perplex City.
I had the most fun working on this project. Together with the wonderful Adrian Hon, Andrea Phillips and David Varela, I created blogs for imaginary people and websites for imaginary businesses and universities, wrote puzzles and clues and did live improvisational writing in front of an online audience. And one summer, not so very many years ago, I found a place in a wood that I thought would be just right for burying a Cube, and so we did.