How to solve this 6×6 logic puzzle

6×6 · steady · 11 steps

This 6×6 board rates as steady (difficulty score 777). Solving it from scratch takes 16 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.

First, every open cell left in this region sits in column 6, so its marker has to land there — clearing every other open cell in the column.
Next, every open cell in row 6 belongs to the same region, so that region's marker has to be somewhere in this row — clearing every other open cell in the region.
Then, together, two regions have open cells only in rows 1 and 2 — with one marker each, those two markers have to fill exactly those two rows, so every other region's open cells there can be cleared.
After that, place a marker at row 3, column 2. Region has exactly one open cell left. Placing here clears the rest of row 3, column 2, and its region. Placing here also clears its 1 touching neighbour.
Now, place a marker at row 6, column 1. Column 1 has exactly one open cell left. Placing here clears the rest of row 6, column 1, and its region.
From there, every open cell left in this region sits in column 5, so its marker has to land there — clearing every other open cell in the column.
Following that, place a marker at row 2, column 6. Row 2 has exactly one open cell left. Placing here clears the rest of row 2, column 6, and its region.
First, every remaining candidate in this region touches row 4, column 4 and row 5, column 4 — so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
Next, place a marker at row 5, column 3. Region has exactly one open cell left. Placing here clears the rest of row 5, column 3, and its region.
Then, place a marker at row 1, column 4. Region has exactly one open cell left.
Finally, place a marker at row 4, column 5. Region has exactly one open cell left.

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