A rare first-edition copy of 'Super Mario 64' just sold for over $1.56 million, making it the most expensive video game in the world - here's why it cost so much

• Over the weekend, a copy of "Super Mario 64" sold for over $1.5 million at auction.
• That's nearly double the next most-expensive game of all time, a rare copy of "The Legend of Zelda."
• "A lot of people are surprised," the CEO of the company that graded the game for auction told Insider. "We are not nearly as surprised."

On July 12, a copy of the Nintendo 64 classic "Super Mario 64" sold at auction for a whopping $1.56 million, instantly making it the most expensive video game on the planet.

For many, the huge price tag for a copy of such a well-known game seemed astronomical. To the CEO of the video game grading firm that rated the game for auction, Ryan Sabga, that price sounded about right.

"A lot of people are surprised," he told Insider in an interview this week. "We are not surprised."

How could a copy of "Super Mario 64," the best-selling Nintendo game on the Nintendo 64 with nearly 12 million units sold, be considered "rare"?

For this particular copy of "Super Mario 64," it comes down to a few very specific details. "The copy that sold is the first print, and to find a first print that was never opened and never played is very, very, very difficult," Sabga said.

The game was given a "9.8 A++" rating by Wata's experts, which you may have noticed isn't a perfect 10.

That's because, with Nintendo 64 games in particular, perfect 10 scores are "an anomaly," Sabga said. "We've done tens of thousands of games. There's only been a handful of 10s."

More than just being in perfect condition, never played, and never opened, the game needs to have been manufactured perfectly to receive a perfect score," he said. "It's really an anomaly to get something like that. So a 9.8 A++ is really the highest achievable grade for all practical purposes."

This is especially problematic with Nintendo 64 games, because "Nintendo 64 games are particularly fragile," he said.

Still, at $1.56 million, this sale is substantially higher than the previous record holder - a record that was set just two days earlier by a copy of "The Legend of Zelda" for the Nintendo Entertainment System, which fetched $870,000 as part of the same auction series.

Rarity is one thing, and value is another.

What's pushing collectors to drop such huge sums for copies of games that can be easily played elsewhere for far less money?

"It's unique starting with this generation," Sabga said. "I think what you're seeing now is a lot of these people who are coming of age, and have made substantial amounts of money, and are just very passionate about this stuff. They love the idea of having essentially a pristine copy of their favorite game that has cultural significance."

Millennials who grew up playing the Super Nintendo and Nintendo 64, he said, are the prime new market. And prices are unlikely to top out at $1.56 million as more Millennials get older and have more expendable income.

"People say, 'I can't believe that there was somebody out there who wanted to pay that much for this," Sabga said. "But that's not exactly true: There were two people willing to pay that, because there needs to be an underbidder to push the winning bidder."

Got a tip? Contact Insider senior correspondent Ben Gilbert via email (bgilbert@insider.com), or Twitter DM (@realbengilbert). We can keep sources anonymous. Use a non-work device to reach out. PR pitches by email only, please.