Loopy Projection 6x6
(Published on 11. January 2026, 13:40 by henter)
I haven't seen this constraint before and don't know if it has a name, so I call it Projection.
Difficulty is probably somewhere between 2 and 3.
Click the image to play
Rules
- Normal Sudoku rules apply.
- Draw a one-cell-wide loop of orthogonally connected cells. The loop may not touch itself, not even diagonally.
- A circle is on the loop and its digit indicates the total number of loop cells in its box.
- A diamond is not on the loop and its digit indicates the total number of loop cells in its box.
- Projection: Each individual loop segment in box N sums to N times the digit in the Nth cell in box 1 (e.g. if r1c3 is 2, then each loop segment in box 3 sums to 3*2).
Enjoy and thanks in advance for ratings and comments!
Solution code: Row 4
Comments
on 15. January 2026, 22:01 by davidz32z
Really fun! I really like the projection rule and I can definitely see the potential with a 9x9 especially with the path going in and out of boxes which I'm not sure is possible in a 6x6. Thanks!
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Thanks for solving and commenting, I'm happy you enjoyed it. Yes, 9x9 definitely offers more flexibility when it comes to loops/paths. I have some ideas for other puzzles with the projection rule as well...
on 11. January 2026, 14:27 by Mr. Happy
I liked it! Projection rule is a bit hard to wrap your head around but once you get it out flows nicely
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Glad you liked it Mr. Happy. In a 9x9 it will is hopefully a bit less confusing as the boxes match up with the projection cells better.
