Color Sudoku Hard

Hard Color Sudoku asks you to hold missing colors in mind across three units at once. When two boxes rule out the same colors, the third one usually breaks the puzzle open. Every cell takes one of nine symbols: .

How to play Color Sudoku

Pick from the nine-color palette so that every row, column and 3×3 box ends up holding all nine colors, each exactly once.

• Each row shows all nine colors exactly once.
• Each column shows all nine colors exactly once.
• Each 3×3 box shows all nine colors exactly once.
• Prefilled colors are fixed clues — everything else you deduce.

Hard Sudoku tips

Locked sets and box-line logic are the workhorses here:

• Lock pairs and triples. When two or three cells in a unit share the same two or three candidates, those symbols are locked there — eliminate them from every other cell of the unit.
• Pointing pairs. If a symbol’s candidates inside a 3×3 box all sit on one row or column, the symbol cannot appear elsewhere on that line. Cut it and re-scan.
• Box-line reduction. The mirror rule: when a line’s candidates for a symbol all fall inside one box, remove that symbol from the rest of the box.

About Color Sudoku

Color Sudoku replaces symbols with a palette of nine colors. Deduction becomes visual — a repeated hue catches the eye faster than a repeated digit — which makes it a favorite for kids and for solvers who want a change of sense, not of logic.

More Color Sudoku levels

Color Sudoku Easy · Color Sudoku Medium · Color Sudoku Expert · Color Sudoku Crazy

About Sudoku

Sudoku is a logic-based, combinatorial number-placement puzzle. In classic Sudoku, the goal is to fill a 9 x 9 grid with digits so that each column, each row, and each of the nine 3 x 3 subgrids that compose the grid contains all of the digits from 1 to 9. The puzzle setter provides a partially completed grid, which for a well-posed puzzle has a single solution.

About Sudokuing

Sudokuing(Sudoku'ing) is an online Sudoku gaming website that focuses on providing a user-friendly, variety of themed Sudoku puzzles for everyone to enjoy.