Here's a slightly cheeky puzzle idea that I'm quite proud of, came up with this not long after the release of Dark Arts
Each row, column, 3x3 box, and the marked diagonal must contain the digits 1 through 9 Solve on F-Puzzles https://f-puzzles.com/?id=296wcd7n
@Guest#f2b1 what was your pencilmarking to get the r8c9 as the only remaining possible place for 4?
congratulations on missing the point, david :)
I was able to solve the puzzle without using uniqueness.
After pencil marking,
Step 1. R8c9 is 4 since whether r2c1 is 4 or 7 it eliminates 4 from c9 in box 3. R8c9 is the only remaining possible place for 4.
This places 8 at r8c7 and 7 at r7d7.
Step 2. 67 must be on the diagonal at r9c1, and c4r6. 8 can only be on the diagonal at r6c4. The 9 must be on the diagonal in box 3. And, r5c8 is 8 by sudoku.
step 3, r5cs is 24, it is 245 by sudoku, but five breaks the puzzle.
step 4, By sudoku 9 is on row 2 of box 2, and, 4 at r2c5 breaks…