Derby Day is a neat take on a flipper game with a horse race theme. The upper playfield contains a single gobble hole and four passive bumpers that can advance one of four horses, whose position is displayed via inserts in the center of the playfield. The bottom portion contains a single pop bumper, which can pop the ball back up to the flippers (in the center portion).
You main goal is to advance all four horses to the Win position, then roll over the center button to earn a replay. You can earn many multiple replays by lining up your horses in Show, Place or Win, then shooting into the gobble hole.
http://ipdb.org/machine.cgi?id=664