Clicking 'New Game' makes an N-by-N table with each cell containing a random integer between Min and Max.
Increment/decrement the numbers row/column-wise.
If the number in a cell is negative, the cell is colored red.
If the number in a cell is zero, the cell is colored blue by default but it can be made green by clicking/tapping.
Each row/column can contain at most one green cell. If you make a blue cell in a row/column that already contains a green cell green, the previously green cell turns blue.
You win if every row/column contains one green cell and no red cell.
