A Medium 6×6 Puzzle Solved with Shape Squeeze in 12 Steps

This 6×6 board rates as medium (difficulty score 806). Solving it from scratch takes 12 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 4, so its marker has to land there; that clears every other open cell in the row.
2. Next, every remaining candidate in this region touches E2, so whichever candidate ends up marked will clear it, and it can be ruled out now regardless of which one wins.
3. Then, every remaining candidate in this region touches D3 and E3 and D5 and E5, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
4. After that, 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.
5. Now, 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. Placing here also clears its 1 touching neighbour.
6. From there, place a marker at D4. Region has exactly one open cell left. Placing here clears the rest of row 4, column D, and its region. Placing here also clears its 2 touching neighbours.
7. Following that, every open cell in row 2 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.
8. First, every remaining candidate in this region touches B5, so whichever candidate ends up marked will clear it, and it can be ruled out now regardless of which one wins.
9. Next, 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. Placing here also clears its 1 touching neighbour.
10. Then, 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.
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.
12. Finally, place a marker at F5. Region has exactly one open cell left.

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