Black cells may not touch the border orthogonally and they may not touch each other orthogonally.
Solve online in Penpa+ (thx Nick Smirnov!)
Solution code: Row 4, followed by row 5. 'S' for a black cell.
on 5. December 2022, 17:23 by Mark Sweep
Very good puzzle!
on 9. October 2022, 08:23 by Richard
Added link and tag for online solving. Thx Nick!
on 25. September 2022, 00:26 by Nick Smirnov
Penpa:
https://tinyurl.com/2gsveu9e
on 22. September 2022, 08:44 by Nick Smirnov
@Richard, could you, please, explain this part of the rules: ''Two orthogonal neighbouring cells from different domino pieces must be equal.'' Can two dominos form a square such that one half of neighbouring cells are equal but the other one is not?
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Reply: No, two dominos can't form a square in this puzzle. All domino halves touching each other must contain equal digits. In the final grid, all domino's have to be placed like in a regular domino game, with the remaining 'holes' filled with black cells.
Here you can find a small example (puzzle 20)
https://logicmastersindia.com/lmitests/dl.asp?attachmentid=360&view=1
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Great, thank you. That will make it easier to solve.
on 1. July 2020, 17:14 by Puzzle_Maestro
Great puzzle! There was a lot of novel logic, at least for me. This type definitely has more potential than I first assumed.
on 3. July 2012, 20:19 by CHalb
Richard, this one is very interesting and quite hard. It took me some time to take the first few notes. After a while I made an assumption in one cell and then - after guessing one number of the solution code ;-) - it took me some more time to finish it. Im going to try if this experience helps me in some other of your Dominos.
on 30. September 2011, 15:12 by ibag
Very nice puzzle, though! Thank you!
on 30. September 2011, 14:50 by Richard
Because I used the wrong image of this puzzle, it had two solutions. With the new image, it must have a unique solution. I sincerely hope!
on 30. September 2011, 14:29 by pin7guin
Yippieh, Erste! ;-)