Great image! Even without noticing all the differnt balls it immediately catched my eye. Having noticed them it is even better! - The balls and the children too are arranged in a way that puts powerful suspense into the composition.
Thank you for the comments all! To answer your question regarding the game, it was a game of two-ball suicide (a more fun version of wallball, wherein you peg the person who fumbles the ball after it bounces off the wall before they can run and place both hands on the wall deeming them "safe".) The football belonged to a second group of kids just out of frame that threw it into the midst.