The Photocopied 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.

Still, a part of you thinks they might be solvable regardless. 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.

• Normal sudoku rules still apply.
• Renban: Digits along a purple line form a set of consecutive digits in any order.
• German whispers: Adjacent digits along a green line have a difference of at least 5 (2 for 4x4 puzzles).
• Equal-sum lines: Box borders divide a blue line into multiple segments which have the same sum. Different lines may have different sums.

Your goal is to figure out what the original solution to each puzzle was. I have transcribed the puzzles below and put them on sudokupad for your ease of solving!

Photocopied Series #1

The first puzzle looks to be a warm-up, a little 4x4. It's probably a good idea to start here and get a sense for how to think about these grey lines. Maybe it'll be a hint for the following puzzles...

This 4x4 will likely provide a hint on how to solve the next puzzles. If you want to challenge yourself, try the other ones first. If you can't make any progress, return to this one for a little hint.

Play online here!

Photocopied Series #2

This puzzle is a full size 9x9 sudoku, with many more lines! To make matters worse, in box 3, a coffee stain has covered 3 cells. You suspect there may have been clues under the stain, but you can't make them out. At least you can make out that there are no lines connecting any of those cells to any of the adjacent uncovered cells (e.g. there is no line connecting R1C8 to R1C7).

Play online here!

Photocopied Series #3 [still being tested]

At least this one doesn't have coffee stains, but surely it will have tricks of its own.

Play online here!