You must shoot all of the red jewels in order to complete the level. Try to collect all of the stars in the process and it will increase your overall score. The fewer shots you take the better your final score will be as well. It is similar to a pinball game because the balls you shoot will bounce around a lot. It's most like a bubble shooter game because you are trying to eliminate the red jewels. You get additional points for the other jewels you destroy too. The other jewels can give you bonuses such as doubling your points or even doubling the ball you shot.