This Wherigo converts your player into a virtual version of the "Reverse Cache Box" which tells you the distance to the cache, but not the bearing. You may begin your search from any spot in the world using your Smartphone or Whereigo compatible GPS to navigate to the cache.
To play you must download the GRAY BUTTE REVERSE WHERIGO from the Wherigo.com website. The download is free.
Your task is to find the cache by periodically querying your Reverse Cache Box for the distance to the final location. Try to use your Reverse Cache Box as few times as possible. All instructions and necessary information needed to complete the cartridge is contained within it. 
If you enjoy this concept and live in Central Oregon, you may be interested in doing these two Reverse Cache TB's owned by Quantum Foam. You will need to contact the CO to get the reverse cache boxes.
Monkey Box
Quantom Foam's Reverse Geocache