🧬 How to play Clone Sudoku
By Miguel Arechaga
Clone Sudoku is a very visual variant where certain areas of the board get "duplicated." Colored regions appear on the grid, and the ones sharing a color are clones: they contain exactly the same numbers, placed in the same position. It's an easy rule to grasp that lets you carry deductions from one side of the board to the other. Here are the rules and a few tips.
What is Clone Sudoku?
It's a standard 9x9 sudoku with several cloned regions. Two regions of the same color have the same shape and must contain the same digits in the same relative positions. It's as if one area of the board were an exact copy of another.
Rules and how to play step by step
- The sudoku rules apply: 1 to 9 without repeats in each row, column and 3x3 box.
- The two regions of the same color are clones: each cell in one region equals its twin cell in the other.
- Filling in a cloned cell sets the same value in its twin. You start with some clues and fill in the rest with logic. Every puzzle has a unique solution.
Tips to solve Clone Sudoku
- Copy and paste: as soon as you deduce a number in one region, it appears immediately in its clone; sometimes that copy solves a box far away.
- The two twins never share a unit: a cell and its clone are never in the same row, column or box (otherwise they'd repeat a number), which helps with elimination.
- Treat the clones as a single block of information: every clue counts twice.
- Combine the clones with the classic elimination techniques of sudoku.
How it differs from regular sudoku
Compared to classic sudoku, Clones introduces equalities between separate areas of the board, in the spirit of other constraint variants but copying entire regions. If you enjoy variants with regions and colors, you'll also enjoy other sudoku variants.
