Cicada 3301
In 1992 the first mysterious puzzle was revealed on 4chan and Reddit. Nicknamed after the handle of the poster, Cicada 3301, were puzzles meant to recruit "intelligent individuals" by presenting a series of puzzles to be solved. The puzzles focused heavily on data security, cryptography, steganography, and Internet anonymity.
The first post is below… 
Hello. 
We are looking for highly intelligent individuals. To find them, we have devised a test.
There is a message hidden in this image. 
Find it, and it will lead you on the road to finding us. We look forward to meeting the few that will make it all the way through.
Good Luck 
3301
The message was accompanied by the famous cicada logo. 
Two more puzzles were released, one in 2013 and 2014. The first and second puzzles were solved but the third remains unsolved to this day 
- Final piece of the Pyramid of Tradecraft! 
- 40 made 36 available
- Glow in the dark! 
Stay Spooky 
~ The Order 💀