Interested in solutions and thoughts on the layout pattern. I know there's been a huge thread on patterns and confess I have not combed it looking for this shape.

- Code: Select all
`5 8 . | . . . | . . .`

. . . | . . . | 5 6 .

7 . . | . 9 1 | . . .

------+-------+------

2 . . | 4 . . | 7 . .

. 4 . | 2 . 5 | . 1 .

. . 6 | . . 3 | . . 2

------+-------+------

. . . | 1 4 . | . . 9

. 1 2 | . . . | . . .

. . . | . . . | . 8 4

Solver stalls here after SSTS and one forcing chain (r4c9=5 [r6c8<>5] r6c2=5 + r8c9=5 [r8c5<>5] r9c5=5 ==> r9c2<>5):

- Code: Select all
`5 8 134 | 367 2367 2467 | 349 3479 137`

139 2 1349 | 378 378 478 | 5 6 137

7 6 34 | 5 9 1 | 2348 234 38

--------------+------------------+---------------

2 359 13589 | 4 168 689 | 7 359 3568

389 4 3789 | 2 678 5 | 3689 1 368

189 579 6 | 789 178 3 | 489 459 2

--------------+------------------+---------------

368 357 3578 | 1 4 67 | 236 2357 9

4 1 2 | 36789 35678 6789 | 36 357 3567

369 379 3579 | 367 23567 267 | 1 8 4

Coloring on 9's lead me to try the assumption that r4c6<>9; while that does not crack the puzzle to SSTS, it does pry it open far enough that some forcing chains/nets can.

Cheers...

- drac