/vr/ - Retro Games

I've boughten the game Mario RPG and a NES Earthbound, and find both games do not play. Both were said to be play tested and worked. The guy I got Mario from wouldn't take the game back and told me he had play tested it. Earthbound I had taken back and was sent another copy. The owner told me the game had been working fine for him, and the next one he sent me had the same issue.

But I have tons of other games that work just fine. So why wont these play?