A Medium 7×7 Puzzle Solved with Shape Squeeze in 13 Steps

This 7×7 board rates as medium (difficulty score 801). Solving it from scratch takes 13 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, place a marker at G2. Region has exactly one open cell left. Placing here clears the rest of row 2, column G, and its region. Placing here also clears its 2 touching neighbours.
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, place a marker at B1. Region has exactly one open cell left. Placing here clears the rest of row 1, column B, and its region.
5. Now, every open cell in row 3 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.
6. From there, together, two regions have open cells only in columns F and E; 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.
7. Following that, every remaining candidate in this region touches C4, so whichever candidate ends up marked will clear it, and it can be ruled out now regardless of which one wins.
8. First, every remaining candidate in this region touches E5 and F5 and F7, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
9. Next, place a marker at F4. Region has exactly one open cell left. Placing here clears the rest of row 4, column F, and its region.
10. Then, place a marker at A5. Region has exactly one open cell left. Placing here clears the rest of row 5, column A, and its region.
11. After that, place a marker at E6. Region has exactly one open cell left. Placing here also clears its 1 touching neighbour.
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.
13. Finally, place a marker at D3. Region has exactly one open cell left.

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