Sudoku is a number puzzle that has a grid of 9 columns and 9 rows. The grid is also subdivided into 9 3x3 blocks. Each block, row, and column must contain all of the numbers 1-9 and can not contain any of the numbers more than once. 32 of the 81 squares starts the game filled out, and the player must use the constraints to fill out the remaining 49 numbers.
**NEW: Several people have requested that I change my sudoku game so that you have to click the cell before the input window pops up. I've made this change and it's now available below. If you prefer the old version of the sudoku game, I have made it available.