Start with the idea
Start with one number and a chain of either-or choices. In this example, the number is 3. One color group must contain the correct 3s, so a 3 that sees both color groups cannot be correct.
Look for this pattern
Look for linked two-choice spots for one number. The links create a pattern you can follow around the board.
This empty board keeps the puzzle numbers out of the way so the pattern is easier to see.
Example
5
3
7
3
6
1
9
5
9
8
6
8
3
6
3
4
1
3
8
7
2
6
6
2
8
3
4
1
3
5
8
7
Look here firstFocus on the number 3. The colored cells form a chain of either-or choices for that one number.
This technique reviews candidates instead of solving a square right away.
The red 3 can see both color groups. No matter which color is correct, that 3 cannot be correct.
- Choose one number.
- Color a chain where each link has exactly two choices.
- Remove that number from a cell that can see both colors.
first colorsecond colornotes to remove
When to look for it
Use it when one note has a chain of two-choice links but no single fish or wing pattern is obvious.
How to use it
- Choose one digit and build a chain through rows, columns, or boxes where it has exactly two possible spots.
- Alternate two colors along the chain.
- Remove notes that touch both colors, or choose the other color if one color breaks the rules.
Common mistakes
- Only color true two-choice links, not any note pair you see.
- Keep the digit fixed throughout the chain.