Created attachment 130740 [details] Two valid solutions for game This shows another game, I believe it is Killer Soduko, with two valid solutions See attachment - game was played to the point where two valid solutions are apparent. Not a software bug, other than in game generation. SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: (available in About System) KDE Plasma Version: KDE Frameworks Version: Qt Version: ADDITIONAL INFORMATION
In Tiny Killer (4x4) and Killer Sudoku (9x9) the 2x2 and 3x3 blocks in the grid each have to contain each digit exactly once, just as in Standard or Classic 4x4 and 9x9 Sudoku. In your attachment, the bottom-left 3x3 block has only one place where a 7 can go. The rest of the unique solution follows from that. See also https://bugs.kde.org/show_bug.cgi?id=421713#c1 and https://bugs.kde.org/show_bug.cgi?id=421713#c4 for a fuller explanation. Also the latest version of the KSudoku Handbook is due to be released this month. It has been updated to explain the finer points of all the variants available in KSudoku. Also you can see the raw source (docbook XML) at https://invent.kde.org/games/ksudoku/-/blob/master/doc/index.docbook. Lines 216 to 333 cover the variant KSudoku games.
*** Bug 425155 has been marked as a duplicate of this bug. ***