Sci-doku is Sudoku with Letters

If you like doing Sudoku puzzles, you will like this variant of the puzzle by Scientific American known as “Sci-doku”. It uses letters instead of numbers. As with normal sudoku, each row, column, and nine-cell grid must contain one and only one of the nine letters. You can not just use any nine letters, you have to use the letters that are already shown on the grid.

Here are the full rules.

Play the Sci-doku games on Scientific American website »