So, here is the Guinness puzzle - Scanraid assures me, as I felt, that it is not-sledgehammer solvable, or reasonable to do in a fast time without bifurcation (guessing). Do it in under 10x the 3:06 time without guessing (let alone the 10 minutes round time) and I'll be amazingly impressed. If anyone ever asks why I hate sudoku competitions but like puzzles, this is a good example. I feel puzzles should be human-solvable, fun, and certainly in a competition serve a purpose of choosing the best, not the luckiest. Sudoku are too easily both computer-generated and made ridiculous, at least in a competition sense, and I've unfortunately stopped bothering to try to always solve logically because I know the rest of the world, in catching up to me, took up bifurcation. This "puzzle" should soundly prove the flaws of "fiendish" puzzles at a sudoku championship if the community of solvers didn't see them before now.
The Art of Puzzles - A fitting sudoku?