A Medium 11×11 Puzzle Solved with Shape Squeeze in 19 Steps

This 11×11 board rates as medium (difficulty score 830). Solving it from scratch takes 19 logical steps, using 7 techniques: Single cell, Row/column exclusion, Adjacency clear, Region confinement, Line confinement, Paired regions, Shape squeeze. Every step below is forced: nothing here is a guess.

1. First, every open cell left in this region sits in row 11, so its marker has to land there; that clears every other open cell in the row.
2. Next, together, two regions have open cells only in rows 9 and 10; with one marker each, those two markers have to fill exactly those two rows, so every other region's open cells there can be cleared.
3. Then, every open cell left in this region sits in row 8, so its marker has to land there; that clears every other open cell in the row.
4. After that, every open cell left in this region sits in row 7, so its marker has to land there; that clears every other open cell in the row.
5. Now, every open cell in column K belongs to the same region, so that region's marker has to be somewhere in this column; that clears every other open cell in the region.
6. From there, every open cell in column I belongs to the same region, so that region's marker has to be somewhere in this column; that clears every other open cell in the region.
7. Following that, place a marker at H6. Column 8 has exactly one open cell left. Placing here clears the rest of row 6, column H, and its region. Placing here also clears its 1 touching neighbour.
8. First, place a marker at J10. Column 10 has exactly one open cell left. Placing here clears the rest of row 10, column J, and its region.
9. Next, place a marker at A9. Region has exactly one open cell left. Placing here clears the rest of row 9, column A, and its region.
10. Then, every remaining candidate in this region touches B3, so whichever candidate ends up marked will clear it, and it can be ruled out now regardless of which one wins.
11. After that, every remaining candidate in this region touches D8, so whichever candidate ends up marked will clear it, and it can be ruled out now regardless of which one wins.
12. Now, place a marker at C8. Region has exactly one open cell left. Placing here clears the rest of row 8, column C, and its region. Placing here also clears its 1 touching neighbour.
13. From there, place a marker at B4. Region has exactly one open cell left. Placing here clears the rest of row 4, column B, and its region.
14. Following that, place a marker at E7. Region has exactly one open cell left. Placing here clears the rest of row 7, column E, and its region.
15. First, place a marker at F11. Region has exactly one open cell left. Placing here clears the rest of row 11, column F, and its region.
16. Next, place a marker at D5. Region has exactly one open cell left. Placing here clears the rest of row 5, column D, and its region.
17. Then, place a marker at G1. Region has exactly one open cell left. Placing here clears the rest of row 1, column G, and its region.
18. After that, place a marker at I2. Region has exactly one open cell left. Placing here clears the rest of row 2, column I, and its region.
19. Finally, place a marker at K3. Region has exactly one open cell left.

The key move here was Shape squeeze. Once you can spot that, this board falls quickly. ∎