During the initial challenges you only have to identify the correct color from four different squares for example, whereas in the later challenges you may have to identify the correct color in 20 squares. There are several different types of challenge including identify the correct color, identify the lightest color, and identify the darkest color. The pallet spread is quite narrow and it becomes increasingly difficult to differentiate between the shades of color. What high score can you register? Are your eyes up to the test?