QED Logic quod erat demonstrandum
Logic Ascent

How to solve this 6×6 logic puzzle

6×6 · gentle · 7 steps

A
B
C
D
E
F
1
2
3
4
5
6
1🐱
2
3
4
🐱
🐱
5
🐱
🐱
6
🐱

This 6×6 board rates as gentle (difficulty score 422). Solving it from scratch takes 14 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, 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 3 touching neighbours.
  3. Then, place a marker at A1. Region has exactly one open cell left. Placing here clears the rest of row 1, column A, and its region.
  4. After 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. Placing here also clears its 2 touching neighbours.
  5. Now, place a marker at F3. Region has exactly one open cell left. Placing here clears the rest of row 3, column F, and its region.
  6. From there, 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.
  7. Finally, place a marker at B5. Region has exactly one open cell left.

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