Latest Changes and Additions

A quick list of the latest updates and additions to this site:

Main Page
Date Created: Thursday 10-Apr-2008
Last Updated: Monday 17-Mar-2025
Strategies for Sudoku, Sudoku X, Killer Sudoku and Jigsaw Sudoku - and the home of logical puzzle maker Andrew Stuart

Sudoku Solver - Version History
Date Created: Sunday 13-Apr-2008
Last Updated: Thursday 13-Mar-2025


What's New
Date Created: Monday 17-Aug-2009
Last Updated: Sunday 9-Mar-2025


XY-Chains
Date Created: Friday 11-Apr-2008
Last Updated: Thursday 6-Mar-2025
Sudoku Strategy. XY-Chains are the work-horse of chaining strategies and are very easy to use when the board contains many bi-value cells. When the start and end cells can see a common candidate eliminations can be made.

WXYZ-Wing
Date Created: Friday 11-Apr-2008
Last Updated: Monday 10-Feb-2025
Sudoku Strategy. WXYZ-Wings extend XYZ-Wings to four numbers and are four cell formations used to eliminate candidate elsewhere. They use a common candidate method to find contradictions.

KenKen Parity Strategy
Date Created: Wednesday 1-Jan-2025
Last Updated: Saturday 1-Feb-2025
KenKen 6x6 strategy that uses ODD/EVEN parities to determine eliminations

Chute Remote Pairs
Date Created: Friday 24-Jan-2025
Last Updated: Thursday 30-Jan-2025
A simple pattern to try early on

Gurths Theorem
Date Created: Saturday 28-Sep-2019
Last Updated: Saturday 25-Jan-2025
Gurth's Symmetrical Placement Theory is discussed

Cage Unit Overlap
Date Created: Tuesday 22-Mar-2011
Last Updated: Tuesday 7-Jan-2025
Killer Sudoku Strategy. Cage Unit Overlap looks at the intersection of a cage with a row, column or box to find eliminations.

Unique Rectangles
Date Created: Friday 11-Apr-2008
Last Updated: Sunday 5-Jan-2025
Sudoku Strategy. Unique Rectangles takes advantage of the fact that published Sudokus have only one solution. There are many formations and strategies based on this notion and they are explained here.