i.Sudoku app for iPhone and iPad

Sudoku - Pretty puzzling.

This is a mathematical game in which players add the numbers 1 to 9 to a 9 × 9 grid, where the numbers in each row, page, and 3 × 3 sub-grid must be unique.

Classic:
Play puzzles you’ve come to love now with 2 difficulty levels to choose from! Elegant, clean and intellectually stimulating. Play at your leisure where every puzzle is freshly generated giving you a never-ending supply of unique classic Sudoku games to play.

Irregular:
Try a whole new take on Sudoku! Rules are the same but the blocks have irregular shapes. You might not ever go back to the classic way of playing again! It’s cool to be Irregular.