Latest Changes and Additions

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

Cell Forcing Chains
Date Created: Saturday 6-Mar-2010
Last Updated: Saturday 18-Oct-2025
Sudoku Strategy. This is a Forcing Chains Strategy. It finds eliminations by comparing the results of two chains starting with a bi-value cell assuming either candidate in the cell is turned on.

Rectangle Elimination
Date Created: Saturday 7-Oct-2023
Last Updated: Saturday 18-Oct-2025
A new tough strategy by Ken Reek

Unit Forcing Chains
Date Created: Saturday 6-Mar-2010
Last Updated: Saturday 18-Oct-2025
Sudoku Strategy. This is a Forcing Chains Strategy. It finds eliminations by comparing the results of chains starting with all candidates N in a unit and assuming any of them are turned on.

Grading Puzzles
Date Created: Tuesday 30-Sep-2025
Last Updated: Monday 6-Oct-2025


BUG
Date Created: Friday 11-Apr-2008
Last Updated: Sunday 28-Sep-2025
Sudoku Strategy. BUG stands for Bi-Value Universal Grave. It is a formation that relies on the uniqueness of the solution and an array of bi-value cells.

Sudoku Min-Lex
Date Created: Monday 22-Sep-2025
Last Updated: Monday 22-Sep-2025

Tridagons
Date Created: Friday 19-Sep-2025
Last Updated: Saturday 20-Sep-2025
The Tridagon or Thor's Hammer is a Sudoku strategy discovered by Denis Berthier

Various Static Patterns
Date Created: Wednesday 14-May-2025
Last Updated: Friday 19-Sep-2025


What's New
Date Created: Monday 17-Aug-2009
Last Updated: Friday 19-Sep-2025


XY-Chains
Date Created: Friday 11-Apr-2008
Last Updated: Friday 12-Sep-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.