February 02, 2011

Sudoku ... in ... Spaaaaaaace!

That's right, everyone: Huzzah! (Or whatever the futuristic sci-fi equivalent of "Huzzah!" is -- "Fraktastic"?) My new book is out today: "Sudoku in Space"! I'm super-pleased with it, and it's available at all your standard online joints such as Amazon and B&N, in real-world bookstores, or from this very blog, if you are the winner of the Exciting Solving Contest below!

All the puzzles in "Sudoku in Space" are sudoku variants (lovingly written by hand), with multicolored grids and extra rules. The puzzles still use sudoku logic, but standard sudoku logic alone won't be enough to finish any of the puzzles; new solving techniques for each variant are required., as you'll discover if you try your hand at these three puzzles, which represent two of the variants. (None of these puzzles appear in the book; I had a few extras left over.)


In this puzzle, each solid colored circle represents a planet, and the hollow circles that match a planet's color represent its moons. The numbers associated with a planet's moons must add up to the planet's number. So, for instance, if a planet had two moons, and the planet's number was 8, its moons could be 1 and 7, 2 and 6, 3 and 5, or 4 and 4.

Lunar Sudoku.png


In these puzzles, you and a counterpart in a parallel universe are both navigating starships whose starting locations are indicated by the blue squares. Both starships are attempting to reach a starbase located at the gray square. Starships may travel horizontally and vertically through vacant squares only -- that is, squares without given numbers in them -- and both ships' paths must contain the same numbers in the same order. (Their starting squares will also contain identical numbers.) The two paths may not intersect.

Parallel Universe Sudoku 1.png

Parallel Universe Sudoku 2.png

To enter the contest, solve all three puzzles by midnight, February 9, and send me your answers; you can scan your printouts and e-mail them to me at f_heaney[this is where the @ symbol goes]yahoo.com, or simply type up your answers. For the Parallel Universe puzzles, either circle the correct paths (if you scan your grids) or list the numbers in the path, in order (if you type your answers). One correct solver selected at random will win a free copy of the book!

(Incidentally, these three puzzles are of medium-to-hard difficulty, so if you get stuck on any of them, don't assume that the book will be too hard for you. Each section starts out with a small tutorial and some easier puzzles to help solvers learn the ins and outs of each variant before the difficulty starts to ramp up ... although, admittedly, once the difficulty does ramp up, whoo boy.)

So there you have it! If you enjoy the puzzles, please spread the word (though if you wish to increase your chance to win by waiting until after the contest deadline to do so, I suppose I understand). Good luck!

Posted by Francis at 12:12 AM

In the parallel universe ones, are the paths allowed to overlap at all?

Posted by: stigant at February 2, 2011 10:40 AM

No, they aren't. I should add that to the puzzle description; thanks for asking.

Posted by: Francis at February 2, 2011 10:54 AM

Just getting to these now Francis -- wow, very fun! Sudoku has always had far more variants than I could have ever imagined, and whenever I think it's all been done...

The Lunar one had some really neat interplay that felt really fresh. I trust I'll have similar comments for the Parallel Universe one. Kudos.

Posted by: JZ at April 16, 2011 11:59 PM

I purchased Sudoku in Space a couple months ago, and I really do enjoy these puzzles. I have hit some that I am stuck on, #38, #40, and #42. I think I found two answers for #40 by making a couple guesses, which brings up a question. Do you recommend guessing if someone is stuck?

Posted by: Chris at July 4, 2011 05:54 PM

Thank you - what a creative set of games, and the way you packaged them in such a "related" manner is itself very creative.

I have found your Asteroid Sudoku VERY challenging. Is there anywhere to get MORE of those puzzles? BTW, how in the world did you come up with that concept (Asteroid Sudoku)?

Posted by: M. Holland at July 9, 2011 04:08 PM

Chris: All the puzzles are solvable without guessing (though some are quite difficult), but there's nothing inherently wrong with making an assumption and seeing if it leads to a contradiction. The puzzle on page 38 is one of my favorites, but it requires a couple of logical steps that hinge on using the variant rules in a newish way. And page 40 definitely has only one solution. I'll e-mail you with some hints if you're still stuck.

M.: Those are pretty much the only Asteroid Sudoku that exist, unless someone else has since tried their hand at writing some. I like those a lot, and would probably have written more for the book, but they all kinda took forever to write. They were inspired by aspects of a few different logic puzzles I like: Nurikabe, End View, and Outside Sudoku (from Thomas and Wei-Hwa's Mutant Sudoku). Partly I wanted to see if I could incorporate a connectivity requirement into a sudoku variant.

Connectivity rules are common in many Japanese-style logic puzzles, like Nurikabe, where the black squares form a connected "river", though Asteroid Sudoku is perhaps more like Corral, where a single fence (that doesn't cross itself) surrounds some area of the grid. End View is sort of like sudoku with empty spaces (for instance, 3 out of 6 squares in each row and column might contain the letters A, B, and C), and letters outside the grid tell you the first letter you see in that direction. And you can find an example of Outside Sudoku in Thomas Snyder's Wired column (and, of course, many more in Mutant Sudoku). So you might try some of those puzzle types if you'd like to try something that's along similar lines.

Posted by: Francis at July 18, 2011 01:14 PM

My understanding Black Hole Sudoku has 1 thru 9 only in the six larger triangles.. Am I correct in assuming this is not true when solving the Black Hole - Warp Surplus? Driving me nuts.....

Posted by: Janet Thibeault at September 22, 2012 07:42 PM

My understanding Black Hole Sudoku has 1 thru 9 only in the six larger triangles.. Am I correct in assuming this is not true when solving the Black Hole - Warp Surplus? Driving me nuts.....

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Posted by: buy cheap wow gold at October 22, 2013 03:10 PM

I cannot even get started on the puzzle on page 28. Other than
eliminating the numbers associated with cells that have the same color. With only 8 numbers and 9 colors, can you provide some guidance?


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