Use keys 1-9. Press a key and then click a box to put it there. All rows and columns must have a sum of 15. You may not use a number more than once. X to restart.
*Remix ideas: *Add a timer - Make time limits to fill it out. *Diagonally - Make everything diagonally also have to equal 15 *4x4 square - Add one more row and one more column to the square
