All 1 entries tagged Sudoku Variants

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June 12, 2009

Friday puzzles #4…

Following its incredible introduction to the world in the finals of the first sudoku world championships in 2006, the toroidal variant gets the pulse of any enthuasiast racing. My effort is in much the same spirit as that original.

The rules are: Fill in each column, row and each region with the numbers 1-9. Some of the regions run off (for example) the top edge of the grid. They continue up from the bottom edge of the grid. Similarly with the left/right edges. The idea is that if you take a nice square, glue left side to right side, and then the top edge – now a circle – to the bottom edge you get a torus – and hence the adjective toroidal. Although if you too are a dabbler in the dark arts of pedantry, you will have noticed that actually a classic sudoku is also “toroidal”. But arguably not as hard. :)

All that is left to be said is this puzzle deserves a slot by itself. Back to two (or more) next week!

#007 toroidal sudoku – rated hard

All puzzles © Tom Collyer 2009

P.S. The next 2-3 Friday’s might suffer some delays too. I’d say there is approximately a 1/7 chance of the puzzles being published on a Friday, but I’ll nevertheless try to keep to the deadline!


Welcome to the blog of current UKPA sudoku champion, two-time Times national sudoku champion and general logic puzzle fan Tom Collyer.

Home of the original Friday Puzzles, each Friday I publish a 100% original and handmade logic puzzle, inspired by the world-famous Nikoli company.

How to play:
AkariFillominoHashiHeyawakeHitoriKakuroLITSMasyuNumberlinkNurikabeRipple EffectShikakuSlitherlinkSudokuSuraromuYajilin.


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Latest comments

  • I like the appearance of the solution. :P Nice one. by Prasanna Seshadri on this entry
  • I think I've seen something vaguely similar in some of Palmer's puzzles as well. To be honest I've a… by on this entry
  • That's two puzzles in a row where I find something I had used before. I know, not plagiarism; just g… by Bram on this entry
  • Kota, that's not really true. I had made my puzzle before going to the WPC already. Also I don't hav… by Bram on this entry
  • About 20 minutes, after restarting from a mistaken conclusion. by Bryce Herdt on this entry

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