Three Balls

It's a toy. Drain the ball and it comes straight back, forever, and the score lives in a debug panel. A game needs an end.

The loop

Real machines all run one loop. A game is a fixed number of balls. Right after a launch comes ball save: drain in the first few seconds and you get the ball back, free. While the ball is alive, every switch it hits builds up a bonus. A drain pays that bonus, times a multiplier, and brings up the next ball. After the last one, it is over.