I want to build a sudoku game with a generator. I have figured out everything how to do it without the difficulty level: easy, medium, hard. My question is how many numbers should I hide depending of the difficulty level? Any ideas.
I'm pretty sure that the difficulty rating for a sudoku puzzle is assigned not based on the quantity of missing numbers but on the techniques required to solve the puzzle.
Take a look at this list of sudoku solving techniques. The Naked Single and Hidden Single techniques are well-known and easy for novices to complete. The harder techniques like X-Wing and Swordfish are much more difficult.
To determine the difficulty, you should write a program that iteratively solves your puzzle, each time with more techniques in its toolbox.