Free sample from Extreme Killer Sudoku 2: step-by-step solution
Print the puzzle first (PDF, A4 or US Letter), then come back and step through the solution, or skip to the hard parts.
Blue digits are placed by the walkthrough. Red strike-through marks a candidate being ruled out. Cells are named by row and column: R3C5 is row 3, column 5. Arrow keys step too.
The key technique: Remote Pairs
A chain of cells that all hold the same pair alternates between the two digits. Cells that see both ends of an odd-length link cannot hold either digit.
Every move above the basics is explained on the killer sudoku techniques page. The book's own 150 puzzles each have a page like this one: all Extreme Killer Sudoku 2 solutions.
The book
Volume two: 150 new killers, none repeated from book 1. No starting digits, just cages and their totals, ramping from hard to brutal.
Try a free sample puzzle (PDF) · prints on A4 or US Letter