For an advanced version of a cavern puzzle, try Wall Sudoku by Phistomefel.
Rules:Normal Sudoku: Place the digits 1 to 9 in every row, column, and 3x3 box. To distinguish the boxes in this puzzle, each 3x3 box is shaded completely grey or completely white.
Cavern Crawl: Orthogonally adjacent digits must have a difference of 3 or less except when separated by a wall (thick black line). Adjacent digits separated by a wall may have any difference. A 3x3 example is provided below.
Solve online:
Solution code: Column 1 followed by Column 9
on 23. June 2023, 16:54 by abadx
first puzzle done with this constraint. It took me 125 minutes without need to bifurcate
on 19. May 2022, 02:01 by Nordy
Puzzle image update.
on 18. May 2022, 01:07 by Nordy
Added walls to the puzzle for a cleaner layout. Intended solution path and solution code unaffected. Additionally, cleaned up up rules text and added link to Phistomefel's cavern-style puzzle.
on 9. January 2022, 01:00 by Mad-Tyas
A very satisfying puzzle!
on 28. November 2021, 17:18 by pipedreambomb
This one was so fun that when I accidentally closed it without copying down the solution code, I just did it again right away!
on 20. November 2021, 04:03 by ddurschlag
Just the right balance of sudoku and other restrictions. Really nice puzzle.
on 5. September 2021, 01:44 by ZetaBean
Worked on this one for quite a while, but I thought the variant was very fun!
—Happy to hear it! I just finished the sequel, which you might enjoy. Similar difficulty but hopefully smoother. Cheers
on 2. September 2021, 15:11 by marcmees
nice variant. thanks.
--Glad you enjoyed! Thanks