I uploaded info on Castle Toy Co Einstein and Mattel Funtronics Red Light Green Light. Both use Nat Semi COP MCUs; RLGL has a COP410L die bonded directly to the PCB, and Einstein has a COP421 (not L). I had to lower the voltage on SI to 1.5v to get the COP421 to go into ROM dump mode. I dumped RLGL both visually and electronically. There's one bit under some dirt, but it's difficult to clean because I don't want to damage the bond wires. I did wind up breaking the bond wire to the green LED; I've been careful with the board, but something must have touched it. Maybe it happened when I removed the plastic that covers the LEDs. www.seanriddle.com/cop410l.html www.seanriddle.com/cop421l.html
I had "Red Light Green Light" (German name = "Stop bei Rot"?) as a kid. It made funny things when battery ran empty. It e.g. only played the finishing siren or repeated strange fragments of the start fanfare (beep-boop - beep-beep-boop-boop - beep-boop...). I thought it would be gate logic with a few shift registers - never expected an actual MCU in such a simple game. I still have it somewhere. It may be that one LED failed in mine too. Is the die directly under that plastic cover or has it additional resin (the infamous soft silicone?) on top? The bolted cover does not look really moistproof, so no surprise if it failed. (The individual naked LEDs may be replaced with a modern SMD LED if they fail.)
I also have an LCD game (shaped like a blue robot with movable black arms) containing such a black cover, that has a pinhole by production fault and the chip makes nonsense.