A Medium 10×10 Puzzle Solved with Shape Squeeze in 16 Steps

This 10×10 board rates as medium (difficulty score 800). Solving it from scratch takes 16 logical steps, using 6 techniques: Single cell, Row/column exclusion, Adjacency clear, Region 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 column J, so its marker has to land there; that clears every other open cell in the column.
2. Next, every open cell left in this region sits in row 9, so its marker has to land there; that clears every other open cell in the row.
3. Then, place a marker at F10. Region has exactly one open cell left. Placing here clears the rest of row 10, column F, and its region.
4. After that, place a marker at I8. Region has exactly one open cell left. Placing here clears the rest of row 8, column I, and its region. Placing here also clears its 1 touching neighbour.
5. Now, together, two regions have open cells only in rows 1 and 2; 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.
6. From there, every open cell left in this region sits in row 3, so its marker has to land there; that clears every other open cell in the row.
7. Following that, together, two regions have open cells only in columns G and H; 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.
8. First, 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. Placing here also clears its 1 touching neighbour.
9. Next, place a marker at D1. Region has exactly one open cell left. Placing here clears the rest of row 1, column D, and its region.
10. Then, place a marker at J2. Region has exactly one open cell left.
11. After that, place a marker at C5. Region has exactly one open cell left. Placing here clears the rest of row 5, column C, and its region. Placing here also clears its 2 touching neighbours.
12. Now, place a marker at B9. Column 2 has exactly one open cell left. Placing here clears the rest of row 9, column B, and its region.
13. From there, every remaining candidate in this region touches G4 and H4, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
14. Following that, place a marker at H6. Region has exactly one open cell left. Placing here clears the rest of row 6, column H, and its region.
15. First, place a marker at G3. Region has exactly one open cell left.
16. Finally, place a marker at A4. Region has exactly one open cell left.

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