There is an omission in the instructions for two of the Jigsaw Extra Regions Sudoku on page 25 of
Sudoku Xtra issue 2. The instructions fail to mention that the regular 3x3 boxes are also present in these puzzles. Without this constraint the bottom-right puzzle will have two solutions. Thank you very much to forum contributor Spittledung for pointing this out!
If you downloaded issue 2 then you can fetch an updated version if you return to the download URL you were originally emailed.
The correct instructions for these puzzles, as now present in the online PDF, read as follows:
Quote
On the bottom two puzzles the 3x3 boxes are still there but are not marked, and additionally bold-lined jigsaw shapes are added that must also contain 1-9. So: place 1-9 in each of the shaded areas, the unmarked regular 3x3 boxes and the jigsaw shapes, plus each of the rows and columns
My apologies to anyone who got stumped by these puzzles! I forgot to draw in the 3x3 regions, and then as a result forgot to mention them in the instructions... and so the puzzles ended up somewhat harder than intended!
If you were an early downloader or have a printed copy you might also have noticed that there is an empty box at the top-left of the Nurikabe solution on page 50 - clearly this should be shaded grey. The puzzle as printed is correct - there is just a left-over box I forgot to fill when drawing the solution, which is also otherwise correct. If you've tried the puzzle I hope this was actually pretty obvious and didn't cause any undue scratching of heads!
