How can a single NES game command a price of $20,100? To put that into perspective, you can buy a super rare Nintendo World Championships Gold cart for around $17,500 and purchase an entire collection of commercially released NES games. With that kind of cash, you can buy every current generation console, pay off a PS4 preorder in full, and have enough change to eat at Ponderosa's buffet.

Unlike the highly coveted Nintendo World Championships carts and Sony's sure-to-be luxury priced PS4, the Nintendo Campus Challenge cart could be a one-of-a-kind item. Originally created by Nintendo for a 1991 video game tournament that visited 58 college campuses, the cartridge contains competition versions of Super Mario Bros. 3, Pin-Bot, and Dr. Mario, in which players have six minutes to play through the games and pick up as many points as possible.

Seller, who claims this is the "most expensive game of all time", describes how the cartridge works: "Once you get 50 coins on Mario 3, you move onto Pin-Bot. Then when you get 100,000 points on Pin-Bot, you move onto Dr. Mario. You play the remaining time on Dr. Mario. After 6 minutes you see a 'Total Score' screen with you combined score from all three games."

As you can see in the above photo, the NES cartridge is modified to allow for a longer PCB board and expose its chips, so the system's lid will need to come off to fit the cart. Two controls are required, one to play the game and the other to hit "Start" for the timer.

While the Nintendo World Championships carts, also produced for a nationwide tournament, were given to competition winners, the Campus Challenge cartridges were supposed to be destroyed after use. This copy, the only one known to exist, was found at an ex-Nintendo employee's garage sale in 2006. You can watch an old news report about the Nintendo Campus Challenge below: