This rare video game is on eBay for $100,000

Nintendo's NES entertainment system
Neil Godwin | GamesMaster Magazine | Getty Images

A rare Nintendo video game from the 1980s has sparked a frantic bidding war on eBay this week, with the item now expected to sell for over $100,000.

Stadium Events is a fitness game made by Japanese firm Bandai in 1987 for the original Nintendo Entertainment System (NES). It is known among industry experts as being one of the the rarest-ever NES games due to a recall by Nintendo, which planned to release it under its own name.

On auction website eBay, the game is described as "complete" and "factory sealed". By midday GMT it had received 81 bids and the current bid was $99,850. The listing is set to end at 3.00 a.m. GMT on Friday morning.

The seller, called menaceone on eBay, wrote on the listing that they used to work at Nintendo and have had the game since the early 1990's.

"Stadium Events is the rarest licensed NES game available thus making a sealed copy one of the most sought after and prized possessions for any video game collector!" according to the post.

Eddie Makuch, news editor at video game website GameSpot, described the game as "super-rare" in an article published Monday. It was originally paired with a mat — called the Family Fitness Fun pad—making it a very early forerunner of the Wii Fit, which Nintendo released in 2007.

"It's considered one of the first exercise games. It's incredibly rare on its own, but adding to the appeal of this auction is the fact that the copy remains factory sealed," Makuch noted in his article

The seller was not immediately available for comment when contacted by CNBC.