I have a mild obsession with the novels of Victor LaValle, including his 2009 novel Big Machine, several editions of which feature cover art of a spiraling line, including the audio edition I enjoyed. I often name puzzles as the last step, but in this case I started with the title and set the puzzle “inspired by” the cover art.
There’s a big green rectangle with some weird edges, and it anchors the grid. But there’s this weird rotating line careening wildly across the grid, with very different properties than the rectangle. It grabs a couple of points, but mostly takes its own path. Oh, and also a switch of sorts, a single black dot. I think of it as a circuit, with the peach line representing temporary wiring. But I’ve used that metaphor when naming other puzzles, so it’s time to pick names differently. Note: Some testers considered this a 1 or 1.5 difficulty, while others rated it 2.5 at least!
Overlapping grids are interesting, but I thought: why always align on thick region borders? What if I split them offset? The answer is: it is a much more difficult puzzle to set, but makes solving more interesting. Trivia: When I set my normal logical auto-solver to the settings I like to use for testing, it gets “stuck” at one particular step. So if you solve the puzzle without using the walkthrough, you’ve done a better job than my logical auto-solver! Even more trivial: The renban lines are almost perfectly symmetrical, but there are two differences.
Each extra region is connected, even if only diagonally. This one should be slightly easier than the last.
Some puzzles include extra regions, but they’re usually square. Or diagonals, which are technically extra regions, and also straight lines. A nine-cell Renban line could be considered an extra region, and can be any arbitrary connected shape. These two regions are none of those.
I tagged this as an XV puzzle, but it’s more than that. It’s not just 5 or 10, or even 15 clues, it’s many arbitrary numbers, all expressed as Roman numerals.
Some lines force digits to be far apart, while other lines force them to be close together. They only interact at a single point.
Quadruples (and Anti-Quadruples) give information about four cells, but these smaller circles only touch two cells, and only contain a single digit each.
Sometimes people just “click,” best friends forever. It happens to digits, too! In some columns, and some rows, certain pairs of digits are inseparable.
Counting is an important skill, in life and in Sudoku. Which is redundant, since Sudoku is life, right?