The articmac,

thank you for your observations and for trying the alpha version mario'sudoku

With regards to the buttons I believe they look good. As I am not aware of any Apple guidelines specifying where they have to be nor their font, spacing or size, could you please tell me where I can find such a rule? Changing the buttons is cosmetic and it would take no time at all.

The preferences are all buttons on the top left hand side of the grid so there is no need for a menu item for them. If the game should get more complicated then I'll activate the preferences menu item which is there, disabled, complying with Apple's guidelines.

With regards to slowness, mario'sudoku can create a sudoku in 6 seconds or less. I do not perceive that to be slow at all compared to the others floating around.
Please tell me what it is slow at doing for you and I will see if I can fix it.
Also please tell me what Mac you use and what OS.

The read me file provided and the help menu explain that there might be different ways of solving a sudoku.
mario'sudoku checks games according to the simple rule that if every row, column and square add up to 45, ie: 1+2+3+4+5+6+7+8+9, then it is correct. The mistakes reported in the dialog box are merely differences between the user and my suggested solution at that stage and perhaps I should call them so in the next release.

This is explained in the read me file. I quote:
"There might be more than 1 solution to a sudoku and I (as the player) have solved the game in a different way than the one created originally."

and later in the same read me:
"Check reports on how you do, hints auto-solutions and mistakes you are currently making according to my (as the programmer) creation of that sudoku. Remember you might still be right and you might be able to solve the sudoku in an alternative way. "

The problem is, a Sudoku puzzle is *required* by definition to only have one possible solution as given. The only way to make progress in a Sudoku puzzle is to prove that there's only one possible number that can go in a particular location. If there's more than one possible solution, then the person won't know whether maybe he's just not finding the one number in the one specific place that he's supposed to be finding, and if he proceeds by guessing, he might be messing himself up later.

There are proper Sudoku-generating algorithms out there; you should replace Mario Sudoku's engine with one of them.

that's right Brian
there is only one solution....
except if you change the givens (revealed tiles) in mario'sudoku you may also be able to find an alternative one but only if you change the givens.
My wife is quite good at that and has already proven to me she often can. That's why I left that option open to players.
The next version will feature a way of locking the givens and then, if the user chooses to play that way, there will be only one solution.
Thank you for pointing out that there are lots of sudokus algorithms out there but I wrote this one myself and that was the real challenge. How to create them in less than 6 seconds. The interface is really simple to implement and fun, but easy too.