Set-to-Zero

In Set-to-Zero the player must set all values on the square board to zero by a sequence of mouse clicks. Every time player click on a positive number, that number is decremented by 1, and four its neighbors are also decremented by 1. If some of the numbers the player attempts to decrement are already zeros, those numbers are set to 4. The player can set the board size from 10x10 through 15x15.