This is what I created for the second challenge. It was really hard to make. :P Click the green flag to generate a new puzzle, and move the slider to change the difficulty. Sadly, the puzzles cannot be played in the project. You'll have to try them on paper if you want to play them. However, I can assure you they are all possible. ;)
Thanks to this wonderful page for lots of help with generating these puzzles! http://blog.forret.com/2006/08/a-sudoku-challenge-generator/
