An Easy 10×10 Puzzle Solved with Paired Regions in 18 Steps

This 10×10 board rates as easy (difficulty score 710). Solving it from scratch takes 18 logical steps, using 6 techniques: Single cell, Row/column exclusion, Adjacency clear, Region confinement, Line confinement, Paired regions. Every step below is forced: nothing here is a guess.

1. First, every open cell left in this region sits in column J, so its marker has to land there; that clears every other open cell in the column.
2. Next, place a marker at I6. Region has exactly one open cell left. Placing here clears the rest of row 6, column I, and its region. Placing here also clears its 2 touching neighbours.
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 column A, so its marker has to land there; that clears every other open cell in the column.
5. Now, together, two regions have open cells only in rows 8 and 9; 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.
6. From there, every open cell left in this region sits in row 7, so its marker has to land there; that clears every other open cell in the row.
7. Following that, place a marker at A10. Region has exactly one open cell left. Placing here clears the rest of row 10, column A, and its region. Placing here also clears its 1 touching neighbour.
8. First, place a marker at B8. Region has exactly one open cell left. Placing here clears the rest of row 8, column B, and its region. Placing here also clears its 1 touching neighbour.
9. Next, together, two regions have open cells only in columns H and G; 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.
10. Then, 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.
11. After that, every open cell in row 1 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.
12. Now, place a marker at E4. Row 4 has exactly one open cell left. Placing here clears the rest of row 4, column E, and its region. Placing here also clears its 1 touching neighbour.
13. From there, 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.
14. Following that, place a marker at J3. Region has exactly one open cell left. Placing here clears the rest of row 3, column J, and its region.
15. First, 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.
16. Next, place a marker at D7. Region has exactly one open cell left. Placing here clears the rest of row 7, column D, and its region.
17. Then, place a marker at C1. Region has exactly one open cell left.
18. Finally, place a marker at H9. Region has exactly one open cell left.

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