A Medium 8×8 Puzzle Solved with Shape Squeeze in 16 Steps

This 8×8 board rates as medium (difficulty score 827). Solving it from scratch takes 16 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 column F, 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 6, so its marker has to land there; that clears every other open cell in the row.
3. Then, 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.
4. After that, 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.
5. Now, place a marker at G3. Region has exactly one open cell left. Placing here clears the rest of row 3, column G, and its region. Placing here also clears its 2 touching neighbours.
6. From there, place a marker at F1. Region has exactly one open cell left. Placing here clears the rest of row 1, column F, and its region.
7. Following that, every open cell in row 4 belongs to the same region, so that region's marker has to be somewhere in this row; that clears every other open cell in the region.
8. First, place a marker at H5. Row 5 has exactly one open cell left. Placing here clears the rest of row 5, column H, and its region.
9. Next, every remaining candidate in this region touches D7 and E7, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
10. Then, together, two regions have open cells only in columns B and C; 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.
11. After that, every remaining candidate in this region touches B7 and B8, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
12. Now, place a marker at C7. Region has exactly one open cell left. Placing here clears the rest of row 7, column C, and its region. Placing here also clears its 1 touching neighbour.
13. From there, place a marker at B2. Region has exactly one open cell left.
14. Following that, place a marker at E6. Region has exactly one open cell left. Placing here clears the rest of row 6, column E, and its region.
15. First, place a marker at D4. Region has exactly one open cell left.
16. Finally, place a marker at A8. Region has exactly one open cell left.

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