A Medium 6×6 Puzzle Solved with Shape Squeeze in 13 Steps

This 6×6 board rates as medium (difficulty score 799). Solving it from scratch takes 13 logical steps, using 5 techniques: Single cell, Row/column exclusion, Adjacency clear, Region confinement, Shape squeeze. Every step below is forced: nothing here is a guess.

1. First, 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.
2. Next, 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.
3. Then, 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.
4. After that, every open cell left in this region sits in row 2, so its marker has to land there; that clears every other open cell in the row.
5. Now, 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.
6. From there, every remaining candidate in this region touches C1 and D1 and C3 and D3, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
7. Following that, place a marker at E3. Region has exactly one open cell left. Placing here clears the rest of row 3, column E, and its region. Placing here also clears its 3 touching neighbours.
8. First, 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.
9. Next, place a marker at C2. Region has exactly one open cell left. Placing here clears the rest of row 2, column C, and its region.
10. Then, every remaining candidate in this region touches B4 and B5, 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 B6. Region has exactly one open cell left. Placing here clears the rest of row 6, column B, and its region. Placing here also clears its 1 touching neighbour.
12. Now, place a marker at A4. Region has exactly one open cell left.
13. Finally, place a marker at D5. Region has exactly one open cell left.

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