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

This 6×6 board rates as medium (difficulty score 800). Solving it from scratch takes 13 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 row 1, 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 row 2, so its marker has to land there; that clears every other open cell in the row.
3. Then, every remaining candidate in this region touches D2 and E2, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
4. After that, place a marker at F2. Region has exactly one open cell left. Placing here clears the rest of row 2, column F, and its region. Placing here also clears its 2 touching neighbours.
5. Now, place a marker at D1. Region has exactly one open cell left. Placing here clears the rest of row 1, column D, and its region.
6. From there, 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.
7. Following that, 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.
8. First, every open cell in row 6 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.
9. Next, place a marker at E5. Row 5 has exactly one open cell left. Placing here clears the rest of row 5, column E, and its region.
10. Then, every remaining candidate in this region touches B3 and B4, 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 A3. Region has exactly one open cell left. Placing here clears the rest of row 3, column A, and its region.
12. Now, place a marker at C4. Region has exactly one open cell left.
13. Finally, place a marker at B6. Region has exactly one open cell left.

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