A Gentle 9×9 Logic Puzzle, Solved in 20 Steps

This 9×9 board rates as gentle (difficulty score 320). Solving it from scratch takes 20 logical steps, using 3 techniques: Single cell, Row/column exclusion, Adjacency clear. Every step below is forced: nothing here is a guess.

1. First, place a marker at I2. Region has exactly one open cell left. Placing here clears the rest of row 2, column I, and its region. Placing here also clears its 2 touching neighbours.
2. Next, place a marker at G1. Region has exactly one open cell left. Placing here clears the rest of row 1, column G, and its region.
3. Then, place a marker at H4. Region has exactly one open cell left. Placing here clears the rest of row 4, column H, and its region.
4. After that, place a marker at F7. Region has exactly one open cell left. Placing here clears the rest of row 7, column F, and its region. Placing here also clears its 2 touching neighbours.
5. Now, 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.
6. From there, place a marker at C5. Region has exactly one open cell left. Placing here clears the rest of row 5, column C, and its region. Placing here also clears its 1 touching neighbour.
7. Following that, 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.
8. First, place a marker at A6. Region has exactly one open cell left.
9. Finally, place a marker at E9. Region has exactly one open cell left.

This was a gentle solve: every step followed directly from placing a marker and clearing its row, column and region. ∎