However, make one mistake and you'll find yourself stuck later on as you get closer to the solution… Try these puzzles, and see if you can solve them too! In addition to the descriptions below a tutorial page is also provided.
Each puzzle consists of a 9x9 grid containing given clues in various places, and one or more of the given clues are located in gray squares. The object is to fill all empty squares so that the numbers 1 to 9 appear exactly once in each row, column and 3x3 box, and all grey squares contain either odd or even numbers according to the given clues.