One step apart
Find the connection between neighboring cells
Consecutive Sudoku keeps the familiar rows, columns and boxes, then adds marks between neighboring cells. Each marked pair must differ by exactly one, in either order. Read any extra rule about unmarked edges before using their absence as a clue.
01
Keep only candidates with partners
For each candidate, look for a digit one higher or lower in the marked neighbor. Remove candidates with no possible partner, then check again.
02
Start with the end digits
A marked neighbor of 1 must be 2; a marked neighbor of 9 must be 8. There is no wraparound between 9 and 1.
03
Leave unmarked edges open unless specified
An empty edge alone does not forbid consecutive digits. Apply that restriction only when the puzzle explicitly says every consecutive pair is marked.