This site contains two different sudoku variants: Code-Doku and Cube Sudoku.

Code-Doku puzzles blend the logical challenge of normal sudoku puzzles with a surprise message that is revealed as you work toward a solution. Instead of using the digits one through nine, Code-Doku puzzles use letters. Other letter-based puzzles such as Go Doku (or Godoku), Sudoku Word or Wordoku have a hidden word, often down the diagonal. Code-Doku puzzles have shaded squares that contain the hidden message. When you have determined the solution to the puzzle, the letters in the shaded squares will spell out the hidden message.

Cube Sudoku puzzles are formed on the six faces of a cube. Each face has a 4×4 grid. The sixteen values must be placed so that each value appears exactly once on each face. In addition, the rows and columns on each face extend all the way around the cube. Each of the sixteen values must also be placed so that each value appears exactly once in each of the twelve strips.

If you'd like to be notified when new puzzles are posted, just send me an e-mail at the address below. For more information about these puzzles, please check out the Code-Doku and Cube Sudoku pages. Good Luck!

Current Code-Doku Puzzle

This puzzle was suggested by Arnie Miller in San Mateo, California.

S

I

C

B

N

E

H

B

C

H

P

C

B

P

B

N

H

I

E

A

B

N

S

P

I

A

S

P

I

B

A Special Treat

Place each of the letters of BE SPINACH exactly once in each row, column and 3×3 box. When you have completed the puzzle, the shaded squares can be read left to right, then top to bottom to form a phrase describing a special treat.

Anagram: BE SPINACH

Difficulty: Easy

Here is a print-friendly version of this puzzle and a solution.

Other difficulties:
All of these can be solved using the sudoku placement rules alone, and they all have the same hidden message. Choose a puzzle difficulty that fits your interest, or solve the easy puzzle then try a harder one after you know the message.

• Medium — Requires no advanced techniques
• Hard — Cannot be solved with elimination alone
• Tricky — Requires something beyond row/box and column/box interactions
• Harder — Cannot be solved with elimination alone
• Fiendish — Requires something beyond row/box and column/box interactions
• Extreme — Requires advanced techniques beyond forced chains

Cube Sudoku

The image below is the current "Easy" Cube Sudoku puzzle. You can get a larger version of this puzzle, the solution, and more difficult puzzles at the main Cube Sudoku page.

Other Sudoku Puzzles and Links