Swipe the number to the position you find good till all numbers are in order. Any order. Starting from the smallest and going up, or the biggest and going down - all that is needed is for the numbers to be in order and you win.
Pick the size of the grid! Anything form 3 by 3, all the way up to 11 by 20 columns and rows. Big grids may be easier to play on a tablet, since the numbers will be quite small on a phone.
Teach a child the order of the numbers and develop imagination by showing them different ways to order the numbers, from the bottom, or going down instead of right.

Play with friends, or waiting for the bus! Enjoy and have fun!