This simple game mimics the popular(?) game you can find in US malls names Stacker!
You just stop the cubes at the right time and they will grow until you make a mistake or you reach the top in which case you won.
To reach the top is almost impossible. That last line is very very hard - if not impossible...
If you don't know the game you can watch YouTube, just search for "Stacker game" - if you wish.