Sudoku

I have spent the past few hours playing around with a Sudoku puzzle generator. I have been pondering creating a game for the Mac that lets you play Sudoku. Seems like a great puzzle game.

The basic idea is to fill in a 9x9 grid with the numbers 1 through 9, where each row contains each of the numbers 1 through 9 and each column contains each of the numbers 1 through 9, and each 3x3 grid within the 9x9 grid contains each of the numbers 1 through 9.

Here's a sample puzzle:

 5 3 - | - 7 - | - - - 
 6 - - | 1 9 5 | - - - 
 - 9 8 | - - - | - 6 -
-------+-------+------ 
 8 - - | - 6 - | - - 3 
 4 - - | 8 - 3 | - - 1 
 7 - - | - 2 - | - - 6 
-------+-------+------ 
 - 6 - | - - - | 2 8 - 
 - - - | 4 1 9 | - - 5 
 - - - | - 8 - | - 7 9

And here is the solution to that sample:

 5 3 4 | 6 7 8 | 9 1 2 
 6 7 2 | 1 9 5 | 3 4 8 
 1 9 8 | 3 4 2 | 5 6 7
-------+-------+------ 
 8 5 9 | 7 6 1 | 4 2 3 
 4 2 6 | 8 5 3 | 7 9 1 
 7 1 3 | 9 2 4 | 8 5 6 
-------+-------+------ 
 9 6 1 | 5 3 7 | 2 8 4 
 2 8 7 | 4 1 9 | 6 3 5 
 3 4 5 | 2 8 6 | 1 7 9

The other thought I had was to take the Sudoku puzzle in a solved mode, and turn it into another kind of puzzle. I'm probably more likely to do that since I think I could apply scoring, and I believe it would be easier to implement the concept of a harder puzzle to solve.

My idea is to take the completed puzzle, and begin to shift rows by 1 spot. The goal of the game would be to return the grid to a completed Sudoku puzzle. As the levels increaese more shifts would be made initially that would need to be undone. Scoring would be similar to Blokz. More points for solving puzzles faster, and the time allotment would be handled similarly to Blokz.