The modern game of sudoku was developed in the end of the 1970's and garnered a large following in Japan during the 80's where it got it's name Sudoku, meaning single number. Sudoku became popular world wide somewhere in 2005. The game of Sudoku is a number puzzle that, in order to solve, must have all the column, rows, and each of the nine 3x3 boxes filled with the numbers 1 through 9.
Not the first Sudoku application to make it to the iPhone, but the Sudoku Guru is by far the best I have seen yet. Sudoku Guru is very simple to follow and you can get playing right away. It offers you 5 different levels of playing starting with the easiest being apprentice, then moving on to intern, then practitioner, then master, and finally, guru. Something that I think is great is something that you don't usually get to do, which is build your own custom game. What I mean by this is Sudoku Guru supplies you with an empty board and allows you to create your own sudoku puzzle and challenge your friends.
Right off the bat you can start solving puzzles. And, with the ability to save a game, Sudoku Guru allows you to start a puzzle during your morning commute on the train and finish it later in the day. Do you want to see how your doing at Sudoku and see how you are progressing? Sudoku Guru supplies you with a statistics page that gives you your best time ever as well as the time it took you to complete your last puzzle. It also supplies you with a help page to explain to you, in detail, everything about the application.
There are two tiny, little things that I didn't like. One would be that they supply you with penciled in numbers that show what numbers are available for use in each box. Personally, I found them very distracting, but it is easily shut off in the options section. Also they have a background noise that I believe was meant to be relaxing, but it's just another distraction. Again, it is easily shut off in the options menu.
With that said, Sudoku Guru still first place on my list of best Sudoku apps.