A Medium 7×7 Puzzle Solved with Shape Squeeze in 16 Steps

This 7×7 board rates as medium (difficulty score 849). 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 E, so its marker has to land there; that clears every other open cell in the column.
2. Next, every open cell in column A 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.
3. Then, every open cell in column B 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.
4. After that, together, two regions have open cells only in columns F and G; 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.
5. Now, every remaining candidate in this region touches D1 and F1 and D2 and F2, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
6. From there, every remaining candidate in this region touches A6, so whichever candidate ends up marked will clear it, and it can be ruled out now regardless of which one wins.
7. Following that, place a marker at D6. Row 6 has exactly one open cell left. Placing here clears the rest of row 6, column D, and its region.
8. First, 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.
9. Next, 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.
10. Then, every remaining candidate in this region touches G3 and G4, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
11. After that, place a marker at G5. Region has exactly one open cell left. Placing here clears the rest of row 5, column G, and its region. Placing here also clears its 1 touching neighbour.
12. Now, place a marker at F3. Region has exactly one open cell left. Placing here clears the rest of row 3, column F, and its region. Placing here also clears its 1 touching neighbour.
13. From there, place a marker at E1. Region has exactly one open cell left. Placing here clears the rest of row 1, column E, and its region.
14. Following that, place a marker at C2. Region has exactly one open cell left.
15. First, place a marker at B7. Region has exactly one open cell left. Placing here clears the rest of row 7, column B, and its region.
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. ∎