Most everyone has probably played avoidance games before. They are generally based on a very simple gameplay mechanic such as moving the mouse cursor around a maze without touching the edges. Some have you moving an object with the keyboard or the mouse while avoiding various shapes that fly about the screen.
In Orb Avoidance, small orbs move directly toward the mouse cursor, though in an elastic-like motion. The first objective is to always avoid the orbs. There are also small gray squares that will pop up randomly from time to time. These are also to be avoided.
By moving the mouse around you will be able to 'fool' the orbs into colliding with the gray squares; doing so destroys the orbs. Clear all the orbs from play to summon the next wave, which always includes 1 additional orb. An additional gray square appears every 5 waves (thanks Khrisper!).
Where the game gets somewhat interesting is when you begin to destroy enough orbs within a short amount of time. The outer edges of the play field begin to 'fill up' with color indicating the rising 'combo'. Continue the rate at which you are clearing the orbs and eventually the combo will fill in its entirety turning red and releasing lots of color with every orb destroyed. This indicates that your score is increasing at its greatest capacity. Keep the combo red and last as long as possible for the greatest score you can.
The random placement of the gray squares will play a large role in how successful you are, so there is a lot of luck to this game. But it's both frustrating and rewarding just enough to be an addictive little game with which to spend 10-15 minutes for a break.