An Expert 11×11 Puzzle Solved with Forced Chain in 32 Steps

This 11×11 board rates as expert (difficulty score 1384). Solving it from scratch takes 32 logical steps, using 8 techniques: Single cell, Row/column exclusion, Adjacency clear, Region confinement, Line confinement, Paired regions, Shape squeeze, Forced chain. Every step below is forced: nothing here is a guess.

1. First, every open cell left in this region sits in column A, so its marker has to land there; that clears every other open cell in the column.
2. Next, every remaining candidate in this region touches J2, so whichever candidate ends up marked will clear it, and it can be ruled out now regardless of which one wins.
3. Then, every remaining candidate in this region touches B10 and B11, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
4. After that, if B1 were the marker, it would force I2 (the last open cell in region 2), then K3 (the last open cell in region 3), and region 6 would end up with no open cell for its marker, which can't happen. So it can't go there.
5. Now, that one can't be the marker: at C1 it would force I2 (the last open cell in region 2), then K3 (the last open cell in region 3), and region 6 would be left with no open cell for its marker.
6. From there, marking D1 would force I2 (the last open cell in region 2), then K3 (the last open cell in region 3), and then region 6 would be left with no open cell for its marker. So D1 can't be the marker there.
7. Following that, if E1 were the marker, it would force I2 (the last open cell in region 2), then K3 (the last open cell in region 3), and region 6 would end up with no open cell for its marker, which can't happen. So it can't go there.
8. First, that one can't be the marker: at F1 it would force I2 (the last open cell in region 2), then K3 (the last open cell in region 3), and region 6 would be left with no open cell for its marker.
9. Next, marking G1 would force I2 (the last open cell in region 2), then K3 (the last open cell in region 3), and then region 6 would be left with no open cell for its marker. So G1 can't be the marker there.
10. Then, that one can't be the marker: at I1 it would force K6, K7, K8, and 10 more cleared (together, two regions have open cells only in columns K and J), then H3, H4, H5, and 3 more cleared (every open cell left in this region sits in column H, so its marker has to land there), then B4, C4, D4, and 3 more cleared (every open cell left in this region sits in row 4, so its marker has to land there), and the chain continues, and region 9 would be left with no open cell for its marker.
11. After that, marking J1 would force K3 (the last open cell in region 3), then I6, I7, I8, and 3 more cleared (every open cell left in this region sits in column I, so its marker has to land there), then H2, H4, H5, and 3 more cleared (every open cell left in this region sits in column H, so its marker has to land there), and the chain continues, and then region 9 would be left with no open cell for its marker. So J1 can't be the marker there.
12. Now, every remaining candidate in this region touches H2, so whichever candidate ends up marked will clear it, and it can be ruled out now regardless of which one wins.
13. From there, if K1 were the marker, it would force I2 (the last open cell in region 2), then J4 (the last open cell in region 6), then B3, C3 and D3 cleared (every open cell left in this region sits in row 3, so its marker has to land there), and the chain continues, and region 8 would end up with no open cell for its marker, which can't happen. So it can't go there.
14. Following that, place a marker at H1. Row 1 has exactly one open cell left. Placing here clears the rest of row 1, column H, and its region. Placing here also clears its 1 touching neighbour.
15. First, every open cell left in this region sits in row 4, so its marker has to land there; that clears every other open cell in the row.
16. Next, together, two regions have open cells only in rows 2 and 3; 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.
17. Then, every open cell left in this region sits in row 5, so its marker has to land there; that clears every other open cell in the row.
18. After that, place a marker at B6. Region has exactly one open cell left. Placing here clears the rest of row 6, column B, and its region. Placing here also clears its 1 touching neighbour.
19. Now, every remaining candidate in this region touches F3 and G3, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
20. From there, every remaining candidate in this region touches D7 and D8, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
21. Following that, every open cell in column D 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.
22. First, place a marker at C8. Column 3 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.
23. Next, together, two regions have open cells only in rows 10 and 11; 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.
24. Then, together, two regions have open cells only in columns I and K; with one marker each, those two markers have to fill exactly those two columns, so every other region's open cells there can be cleared.
25. After that, place a marker at J3. Region has exactly one open cell left. Placing here clears the rest of row 3, column J, and its region.
26. Now, place a marker at F2. Region has exactly one open cell left. Placing here clears the rest of row 2, column F, and its region.
27. From there, place a marker at G4. Region has exactly one open cell left. Placing here clears the rest of row 4, column G, and its region.
28. Following that, place a marker at E9. Region has exactly one open cell left. Placing here clears the rest of row 9, column E, and its region. Placing here also clears its 1 touching neighbour.
29. First, place a marker at K7. Region has exactly one open cell left. Placing here clears the rest of row 7, column K, and its region.
30. Next, place a marker at I5. Region has exactly one open cell left.
31. Then, place a marker at D11. Region has exactly one open cell left. Placing here clears the rest of row 11, column D, and its region.
32. Finally, place a marker at A10. Region has exactly one open cell left.

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