I've designed a set of dominoes puzzles that I call Donimoes. You slide the dominoes like the cars in Nob Yoshigahara's Rush Hour puzzle, always along their long axis. The goal of Unmatched Donimoes is to slide all the dominoes into a rectangle, without sliding any matching numbers next to each other. See Monday's problem for complete rules and and an example solution. Tuesday's problem would make a good warmup.

Today's problem is a little bigger and a little harder. Good luck, and post your solution as an answer.

starting position

If you like this puzzle, watch for new problems every day this week.

  • $\begingroup$ Is there a limit to how far the dominoes can slide? i.e. Is there a bounding box? If not, it should be trivial in most cases just to slide all the dominoes out into the surrounding area until there is ample space between them all, and then they can easily be rearranged into any configuration you like without running afoul of other dominoes. $\endgroup$ Jul 24, 2019 at 15:29
  • 1
    $\begingroup$ @GentlePurpleRain "All the dominoes in the puzzle have to be connected in one solid group, diagonal connections don’t count." So the dominoes must form a contiguous set at all times. $\endgroup$
    – hexomino
    Jul 24, 2019 at 15:32
  • $\begingroup$ @hexomino Thanks. I guess I should have looked at the complete rules before posting questions that have already been answered.... $\endgroup$ Jul 24, 2019 at 15:43
  • $\begingroup$ After I designed the rules, @OmegaKrypton, I found it hard to design new problems. I wrote a computer program that uses evolutionary search to find interesting problems. You can read my making Donimoes post, if you want more details. $\endgroup$
    – Don Kirkby
    Jul 25, 2019 at 2:37

1 Answer 1


The first order of business is to slide the 12 domino out of the way so that we can slide the 13 domino to the right:

22UU, 16UU, 34RR, 00DD, 25R, 45R, 12D, 13RR

That having been done, we can now push everything else from the centre back where it came from:

12U, 45L, 25L, 00UU, 34LL

and then form a rectangle:

16D, 22D, 03U, 14U

and the puzzle is solved (assuming I haven't made any mistakes, which may well be the case given that I don't have a set of dominoes with me).

  • $\begingroup$ Nice answer! I like your compressed notation when a domino moves twice. $\endgroup$
    – Don Kirkby
    Jul 25, 2019 at 2:55

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