Wikipedia: "Cicada 3301 is a name given to an enigmatic organization that on three occasions has posted a set of complex puzzles and ARGs to recruit capable cryptanalysts from the public.
"The first Internet puzzle started on January 5, 2012 and ran for approximately one month. A second round began exactly one year later on January 5, 2013, and a third round is ongoing following confirmation of a fresh clue posted on Twitter on 5 January 2014. The stated intent was to recruit "intelligent individuals" by presenting a series of puzzles which were to be solved, each in order, to find the next. The puzzles focused heavily on data security, cryptography, and steganography."