One of the most challenging aspects in writing a puzzle (after coming up with the overall idea) is communicating the underlying mechanics to you, my puzzle-solving audience. The instructions for a puzzle need to be thorough and unambiguous, yet clear and concise. It’s typically one of the last things that I complete, since making the puzzle helps refine the instructions, and then preparing it for publication brings up interpretations that I had never thought of.
I ran across this puzzle in my file of stuff that I’ve created in the past, but I can’t seem to find the instructions for it. Apparently this is the shortest solution, and some incorrect solution attempts. Can you help me write out what the instructions for this puzzle should be?