Square Lines is a free point scoring game that's designed to test your reflexes. Look at the very top of the image. See the square? From the right, a green line is coming. You must quickly rotate the square so that the green side will catch the green line.
There are 4 levels of difficulty. The easiest: there is only 1 square to deal with. The hardest: 4 squares at the same time.
We should all be playing games like this every so often to ward off Alzheimer's.