Cool! The patent shows a COP421L, which is easy to electronically dump.
Mattel Auto Race does have a Rockwell B6000 chip as I suspected (BSG is B6001), and Football 2 has a new one: Rockwell B8000, which is a 40-pin DIP.
Three more: Castle Toy Co. Einstein (Simon clone) has a COP421, so that should be easy to dump. Tandy Baseball has a PIC1650A- maybe I can dump this one; I know Kevin can. Atari Touch Me has an AMI chip labeled C10745. I haven't checked the pinout yet to see if it's standard or custom.