13th August 2024:
I wrote my sudoku creation program back in 2012.
Then in 2022 I decided to publish a book of tough puzzles. I used my program to create puzzles again and again and passed each one to HoDoKu. I stored puzzles with a HoDoKu grade between Hard (1000) and Hard (1999) and discarded the rest. After I had created around 8000 puzzles I had the 400 tough / hard puzzles I needed for my book.
You can buy my book using the advert on this page.
Alternatively, for a chance to win a copy, solve the sudoku below. It has a HoDoKu grade of Hard (1490) so it is typical of the puzzles in my book. Send your answer to me at international_dba@yahoo.co.uk. Do not send me your address at this point. The closing date for entries is 31st October 2024. On 1st November 2024 I will choose one winner at random from all the correct solutions received and ask where to send the book.
The name of the winner and the solution will be published shortly afterwards.
1st November 2024:
This competition is now closed.
3rd November 2024:
The winner is Freddy Vargas from Colombia.
