Basic Circle Game

An easier PK game, this is one of the 'push in one direction or the other' exercises. 

Circles drop from across the top of the field of play in a pseudo-random fashion. If they hit the left side or the left half of the bottom of the field of play, the score goes up. If they hit the right side or the right half of the bottom, the score goes down. 

Choose a side, and push the dots over there. The object of the game is to get a score as far from zero as possible, in either direction.

(fixed the side-score problem)