It has been called the worst video game ever made – but thousands of people are expected to bid to get their hands on a copy.
ET - based on the hit movie and released in 1982 - was said to be so bad that Atari buried a million unsold copies in shame at a New Mexico rubbish dump.
A major dig in April this year uncovered 1,300 copies of the release, proving that the story was true, and not just an urban myth.
Now more than half of the vintage video game haul is to be auctioned in the run-up to Christmas.
Members of the Alamogordo City Council voted 7-0 to offer the Atari games found for sale on eBay and the council's own website.
Dig site supervisor Joe Lewandowski said the excavation was like seeing a "phoenix rising from the desert".
He said: "It was like the beginning, end, and a new beginning for the video game industry when we found these games."
The unearthed games are under the custodianship of the Tularosa Basin Historical Society and stored at the New Mexico Museum of Space History in Alamogordo, 200 miles southeast of Albuquerque.
The city plans to keep some of the games as mementos, and the rest of the cartridges will be donated to museums around the world. Mr Lewandowski added: "We've already heard from the Museum of Rome, which has a section for video games." The sale is due to begin in two weeks and be complete by Christmas.
ET flopped after being rushed out to coincide with the release of the Steven Spielberg movie, and contributed to a collapse of the video game industry in its early years.
The mystery behind why the games were dumped in the landfill inspired a documentary film by Microsoft Corp's Xbox Entertainment Studios.