Could anyone tell me what this is? I see lots of posts and links I don't understand.
It's a competition, LF enters a team every year. The puzzles come in sets of four or so, one set released each day for a week. The object is to find the answer to the puzzle (in the form of a word or short phrase, IIRC), and submit the answers before the day is over.
The puzzles are quite cryptic -- they typically don't give any obvious indication as to how to attain an answer from it. Last year, one of the puzzles was just a piece of sheet music -- guessing how the answer is encoded in the sheet music is part of the challenge.