An Easy 9×9 Puzzle Solved with Region Confinement in 12 Steps

This 9×9 board rates as easy (difficulty score 449). Solving it from scratch takes 12 logical steps, using 4 techniques: Single cell, Row/column exclusion, Adjacency clear, Region confinement. Every step below is forced: nothing here is a guess.

1. First, 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. Placing here also clears its 2 touching neighbours.
2. Next, place a marker at G2. Region has exactly one open cell left. Placing here clears the rest of row 2, column G, and its region. Placing here also clears its 2 touching neighbours.
3. Then, place a marker at C8. Region has exactly one open cell left. Placing here clears the rest of row 8, column C, and its region. Placing here also clears its 2 touching neighbours.
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, 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. Placing here also clears its 1 touching neighbour.
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 F, so its marker has to land there; that clears every other open cell in the column.
8. First, place a marker at H9. Region has exactly one open cell left. Placing here clears the rest of row 9, column H, and its region.
9. Next, place a marker at I7. Row 7 has exactly one open cell left. Placing here clears the rest of row 7, column I, and its region.
10. Then, place a marker at F5. Row 5 has exactly one open cell left. Placing here clears the rest of row 5, column F, and its region. Placing here also clears its 1 touching neighbour.
11. After that, place a marker at E3. Region has exactly one open cell left. Placing here clears the rest of row 3, column E, and its region.
12. Finally, place a marker at A4. Region has exactly one open cell left.

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