The game requires some intense concentration, and you'll do best if you're comfortable with the action on-screen. You can change brightness settings by tapping the icon that looks like a lightbulb on the menu screen, and you can also adjust the color of the ball with in-game purchases using the gems you gather. Your choice of color can make it easier to see the helpful shadow... or more difficult. Try for fairly neutral color tones if you want the easiest time of things.