A Steady 8×8 Puzzle Solved with Shape Squeeze in 16 Steps

This 8×8 board rates as steady (difficulty score 823). 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.

1. First, together, two regions have open cells only in columns G and H; with one marker each, those two markers have to fill exactly those two columns, so every other region's open cells there can be cleared.
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 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.
4. After that, 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.
5. Now, 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.
6. From there, every open cell in column A belongs to the same region, so that region's marker has to be somewhere in this column; that clears every other open cell in the region.
7. Following that, every remaining candidate in this region touches E3, so whichever candidate ends up marked will clear it, and it can be ruled out now regardless of which one wins.
8. First, every remaining candidate in this region touches C4 and D4, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
9. Next, place a marker at B4. Region has exactly one open cell left. Placing here clears the rest of row 4, column B, and its region. Placing here also clears its 3 touching neighbours.
10. Then, place a marker at D3. Region has exactly one open cell left. Placing here clears the rest of row 3, column D, and its region. Placing here also clears its 1 touching neighbour.
11. 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 1 touching neighbour.
12. Now, place a marker at H1. Region has exactly one open cell left. Placing here clears the rest of row 1, column H, and its region.
13. From there, place a marker at C6. Column 3 has exactly one open cell left. Placing here clears the rest of row 6, column C, and its region.
14. Following that, place a marker at G5. Region has exactly one open cell left. Placing here clears the rest of row 5, column G, and its region.
15. First, place a marker at E7. Region has exactly one open cell left. Placing here clears the rest of row 7, column E, and its region.
16. Finally, place a marker at A8. Region has exactly one open cell left.

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