Did you ever notice the wheels on the car driving next to you sometimes appear to be spinning backwards? This is referred to as the stroboscopic (or wagon-wheel) effect. It occurs when an object is rotated at certain speeds, making the object to appear to stop or even go backwards.
Rotate 4 different objects in either direction (clockwise or counterclockwise). You can increase the speed until you see it appear to stop or reverse.
On one of the objects, a wheel with different colored alternating rings, you can make it appear as if the rings of this single option are turning in opposite directions.
Universal App - supports native iPad, iPhone and iPhone 4's Retina display.
WARNING - Those with Epilepsy or those subject to seizures are usually cautioned to avoid strobe lights or similar effects.