The main portion of the puzzle consists of nine “mastermind” logic puzzles, in which the goal is to determine a six-letter word. For each “guess,” a black circle is provided for each correct letter in the correct position, and a white circle for each correct letter in an incorrect position. All of the guesses are words (some capitalized) with no repeated letters, and the same is true for all the solutions, though each can be solved uniquely without that assumption.
The solutions to these nine puzzles are:
Reading down the first and last letters of these words in order reveals the message SEE RECENT GMPUZZLES. Grandmaster Puzzles is a logic puzzle site hosted at gmpuzzles.com. Investigating the site’s blog, where puzzles are posted on a regular basis, reveals that on four consecutive mornings leading up to the Hunt (January 15–18, 2019), the site has posted four cipher fillomino puzzles by debut constructor Tim Marsden. The fact that TIM MARSDEN is an anagram of MASTERMIND should hopefully suggest that these are the right puzzles to look at.
Here are the four puzzles and their solutions:
The puzzle also includes a 10×10 grid of letters, and after solving these puzzles, the solver has four additional letters assigned to each position as well, one from each of the four puzzles (for example, the upper left square has a B, M, N, and H). To emphasize that these are the right combinations of letters to look at, and that you might need to rearrange these letters, the eighth square in the seventh row (which contains the letters C, E, D, and O) is marked CODE.
In each of the mastermind puzzle answers, there are four internal letters that haven’t been used yet, and in each case, these four letters appear (in the four puzzles, but not necessarily in order) in one of the positions. Using the letter in that position of the grid given with the puzzles, each of these positions can be converted into a letter.
These letters spell the answer to the puzzle, COTENANCY.