Between Lines Sudoku
Digits on a line must fall strictly between the two endpoint values
Between Lines Sudoku is fully playable. Choose a difficulty and start solving.
Between Lines Sudoku draws lines with circular endpoints. Every digit along the line (excluding the endpoints themselves) must be strictly greater than the smaller endpoint and strictly less than the larger endpoint. If the endpoints are 2 and 8, every middle cell on the line must be one of 3, 4, 5, 6, or 7. The closer the endpoints are in value, the more constrained the middle cells.
Like all Sudoku variants, Between Lines Sudoku builds on the classic 9×9 foundation. Every row, column, and 3×3 box must contain each digit from 1 to 9 exactly once. The variant constraint is added on top of these standard rules, never replacing them.
If you're new to Sudoku, start by learning the basic rules and techniques before attempting variants.
Techniques Useful for This Variant
| Technique | How it applies |
|---|---|
| Pencil Marks / Notes | Essential for tracking candidates alongside the variant constraint |
| Obvious Singles | Cells narrowed to one candidate by the combined constraints |
| Hidden Singles | Digits with only one valid cell in a unit after variant elimination |
| Pairs and Triples | Locked candidates exposed by the additional constraint |