A Medium 7×7 Puzzle Solved with Forced Chain in 11 Steps

This 7×7 board rates as medium (difficulty score 895). Solving it from scratch takes 11 logical steps, using 6 techniques: Single cell, Row/column exclusion, Adjacency clear, Region confinement, Shape squeeze, Forced chain. Every step below is forced: nothing here is a guess.

1. First, 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.
2. Next, place a marker at C2. Region has exactly one open cell left. Placing here clears the rest of row 2, column C, and its region. Placing here also clears its 2 touching neighbours.
3. Then, place a marker at A3. Region has exactly one open cell left. Placing here clears the rest of row 3, column A, and its region. Placing here also clears its 1 touching neighbour.
4. After that, every remaining candidate in this region touches E4 and E5, so whichever candidate ends up marked will clear them, and they can be ruled out now regardless of which one wins.
5. Now, marking G1 would force B7 cleared (every open cell left in this region sits in row 7, so its marker has to land there), then B6 cleared (every open cell left in this region sits in row 6, so its marker has to land there), then B5 (the last open cell in column B), and the chain continues, and then row 7 would be left with no open cell for its marker. So G1 can't be the marker there.
6. From there, place a marker at F1. Region has exactly one open cell left. Placing here clears the rest of row 1, column F, and its region.
7. Following that, place a marker at D4. Region has exactly one open cell left. Placing here clears the rest of row 4, column D, and its region.
8. First, 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.
9. Next, place a marker at E6. Region has exactly one open cell left. Placing here clears the rest of row 6, column E, and its region.
10. Then, place a marker at B5. Region has exactly one open cell left. Placing here clears the rest of row 5, column B, and its region.
11. Finally, place a marker at G7. Region has exactly one open cell left.

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