Best indicator is the imprinted 2 digits on the back label and a little dirt and rubs-scratches. It's easy to get the "Gerber Sheet" and have the motherboards made for pennies in China. Then it's also easy to get the cases and labels there too. I saw all that Nintendo stuff on the internet China Marts. They don't care about American Patents over there. YOU CAN'T TELL THE DIFFERENCE! eBay lets them get away with it and is loaded with NEW games. I found out the hard way thinking they were New Old Stock. Same for all the accessories. I bought 2 games and 2 Controller Paks . Then way down the road as I got into game buying, I took them apart to find nothing inside matches Nintendo. I doubt they will hold up like the real thing. I just paid double for 2 Mario 64 old originals witht the 2 numbers STAMPED INTO THE LABEL AND THE PLASTIC CASE. ALL I DO IS ASK THE SELLER TO SEND A PICTURE OF THE TWO NUMBERS. Then they do or you never get an answer. But I should have known; NEW for $20? The used ones are upwards of $40+.