Hoard Hunter (v0.9) is a WordPress / WordPress MU plugin with integrated theme that powers an online treasure hunt game.
I am running the initial game at http://hoardhunter.com to raise funds for Oxfam and the Gurkha welfare trust and it was originally developed to go alongside the other fund raising I am doing (see: http://hoardhunter.com/about/ for more details).
It is designed to allow people raising money for charity to have an easily set-up (and hosted if required) online treasure hunt game.
More details on the system can be found here:
I am currently monitoring the game to make sure it functions correctly (as transparency is vital in this type of system), once I am confident I will make a download available.
Please let me know what you think of the concept, idea, site, etc..