How to Play Renban Sudoku

Renban Sudoku is a variant where purple lines are drawn across the grid. Every purple line must contain a set of consecutive digits (in any order along the line). For example, a 4-cell renban line might hold 3,4,5,6 or 6,4,5,3 — any arrangement, as long as the set forms a run of consecutive numbers. Standard Sudoku rules apply.

No. The digits on a renban line must form a set of consecutive numbers, but they can appear in any order along the line. A 3-cell renban line holds three consecutive digits arranged in any sequence — it's the set that matters, not the sequence.

No. Because the digits must form a consecutive set and each digit in a set is unique, no digit can repeat on a renban line. This is an implicit constraint: a 4-cell renban line always contains exactly four distinct consecutive digits.

Start with the shortest lines and look for lines that share cells with highly constrained rows, columns, or boxes. A 2-cell renban line can only hold adjacent digit pairs (1&2, 2&3, ..., 8&9). Identifying which consecutive set fits each line, then cross-referencing with standard Sudoku constraints, is the core technique.

Easy and medium renban puzzles are comparable in difficulty to classic Sudoku at the same level. Hard and expert puzzles become significantly harder because you must track which consecutive sets are possible for multiple overlapping lines simultaneously, which requires combinatorial thinking on top of standard Sudoku logic.

Easy puzzles take 8–18 minutes. Medium puzzles run 18–35 minutes. Hard puzzles average 35–60 minutes and expert puzzles can take over an hour. Solve time is most affected by the number and length of renban lines — more lines mean more interacting constraints.