Atlantis 2, not to be confused with the true sequel to Atlantis, Cosmic Ark
, is a modified reprint of the original game by Imagic. Shortly after Atlantis released Imagic began a contest called Destination Atlantis. Player's had to send in photos of the high scores they've earned in Atlantis in order to enter. The top scoring players won a copy of Atlantis 2 which was never sold at retail.
The game was the same as the original but the enemies were faster and earned the players less points.
Atlantis 2 leverages all the packaging of the original game. The box art, and cartridge and re-purposed Atlantis cartridges. The only difference is that white stickers which say "Atlantis II" have been put on the front of the box and cartridge.
Because of how the game was distributed, it's very rare. Auctions for Atlantis 2 go for over $5,000.