Take the black balls to the blue circles to pass the level. It's complete when each blue circle has a black ball. The yellow circles reduce the ball's speed and the pink circles are force fields that attract or repel them; the big black circle is a black hole that removes the balls from the game, but if too many are removed you'll not be able to cover the blue circles and will lose. Progress to the end through 36 levels of increasing difficulty.
Click and drag over the gameboard to tilt it to one side or the other and so make the ball to roll.