A Medium 7×7 Puzzle Solved with Shape Squeeze in 15 Steps

This 7×7 board rates as medium (difficulty score 824). Solving it from scratch takes 15 logical steps, using 6 techniques: Single cell, Row/column exclusion, Adjacency clear, Region confinement, Line confinement, Shape squeeze. Every step below is forced: nothing here is a guess.

1. First, every open cell left in this region sits in column B, 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 B2, so whichever candidate ends up marked will clear it, and it can be ruled out now regardless of which one wins.
3. Then, place a marker at B3. Region has exactly one open cell left. Placing here clears the rest of row 3, column B, and its region. Placing here also clears its 4 touching neighbours.
4. After that, every open cell left in this region sits in row 1, so its marker has to land there; that clears every other open cell in the row.
5. Now, place a marker at D2. Region has exactly one open cell left. Placing here clears the rest of row 2, column D, and its region. Placing here also clears its 1 touching neighbour.
6. From there, place a marker at A1. Region has exactly one open cell left. Placing here clears the rest of row 1, column A, and its region.
7. Following that, 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.
8. First, every open cell left in this region sits in column C, so its marker has to land there; that clears every other open cell in the column.
9. Next, every open cell in row 7 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.
10. Then, every remaining candidate in this region touches F4 and F5, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
11. After that, every remaining candidate in this region touches F6, so whichever candidate ends up marked will clear it, and it can be ruled out now regardless of which one wins.
12. Now, 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.
13. From there, place a marker at E5. Region has exactly one open cell left. Placing here clears the rest of row 5, column E, and its region.
14. Following that, place a marker at C6. Region has exactly one open cell left.
15. Finally, place a marker at F7. Region has exactly one open cell left.

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