The rules
- Never put 3 matching numbers together, across or down.
- Each row and column needs as many 0s as 1s.
- Keep rows different and columns different; a row may match a column.
Two worked examples
Two 1s sit side by side in a row. The box next to them cannot be a 1, or three 1s would sit together. So it takes a 0.
Say a row has six boxes and three of them are already 1. Half the boxes are 1s, so every empty box in that row takes a 0.
Playing it in Quirk
Fill each box with 0 (a ring) or 1 (a disc with a slit).
Pick 0, 1 or Erase, then tap a box or drag across several boxes.