This is part 4 in a series of related puzzles. You don't need to solve the others before trying this one. You can see all the puzzles in this series on my website at kammer.xyz/blog/sudoku/photocopied.
You can also visit the logic-masters pages for the other puzzles in the series:
You have been gifted a large collection of puzzles from a friend. You sift through them looking for interesting ones and find photocopies of puzzles from an old book of puzzles, filed under "puzzles with no given digits". The original book is nowhere to be found and the photocopies are in black and white.
You assume the original had a unique solution, but can you still reconstruct that solution? The rules below are listed for the entire section of puzzles, so you can't be sure whether all three line types actually exist in any of the puzzles.
Your goal is to figure out what the original solution to each puzzle was. I have transcribed this puzzle and put it on sudokupad for your ease of solving!
Solution code: Top row, left to right
on 6. September 2026, 21:53 by QuiltyAsCharged
I came across this puzzle because it was featured on CTC a day or two ago. It's a lovely idea, and really stretched my brain because I'm not used to thinking about uniqueness in this way.
Also, I really like the presentation on your blog where you have the photocopies on display!
Please note: The German version of this page has changed. It is possible that this page does not contain the latest information.