Will Shortz is NOT a puzzle. He is a puzzleR, and there is a vast difference between the two. I would suggest you substitute him with something like crossword or sudoku.

I think you're being entirely too literal. Puzzles are the linking concept. Riddles and puzzles don't have to be games per se. If you look at all 4 categories, two are clearly related as problematic things looking for a solution or definition or clarity and two are modes for achieving some structure or organization . It's two sets of pairs. The theme was PuzzGrid: a tension between the structureless or unsolved and the structured or solved. I admit the grid isn't perfect, but I stand by the concept.