Atlantis is a fixed shooter video game produced by Imagic in July 1982, for the Atari 2600 video game console. The game was subsequently ported to the Atari 8-bit family of home computers, the Commodore VIC-20 home computer, the Intellivision, and the Magnavox Odyssey².

Atlantis is a variation on the shooting game genre popular in the early 1980s. The player controls the last defenses of the City of Atlantis against the Gorgon invaders. The city has seven bases, which are vulnerable to attack. Three of these have firepower capabilities to destroy the Gorgon ships before they manage to drop bombs on one of the settlements. The gun bases have fixed cannons; the center base fires straight up, while the far left and far right bases fire diagonally upwards across the screen. The enemy ships pass back and forth from left to right four times before they enter bombing range, giving an ample opportunity to blow them away. Lost bases can be regained by destroying enough Gorgon ships. However, regardless of the player's efforts to avert the tragedy, Atlantis is doomed. The only way the game can end is when all bases are destroyed. However, a tiny ship then rises from the rubble and speeds away, foreshadowing the events of the sequel Cosmic Ark.

The Intellivision version features two gun turrets with a movable cursor that can be aimed onto enemy ships. There is also a deploy-able ship to take on enemies one-on-one. The game features day, dusk, and night settings, with the night setting limiting visibility to two moving searchlights.

Imagic created Destination Atlantis, a high score competition in which players were invited to send in pictures of their high score screens. Those with the highest scores were rewarded with a copy of Atlantis II.

It should be noted that Atlantis II was a competition cart for the top ten Defend Atlantis contestants. There were originally only supposed to be four people in this competition, but because Imagic needed the top ten players who scored above five million points to be only four players, they came up with this tie breaker cartridge to weed out the weaker players. Only ten of these cartridges were specially made with the same rom set, costing Imagic only a few thousand dollars to produce by making slight changes to the original mask, as opposed to making a brand new Rom from scratch. Those who turned the game score over to 1,000,000 points five times or more would receive the competition cartridge. The score would reflect this with the last digit turning over each time one million points was scored, whereas the ones place on the screen would advance by one place. So a person with a score of 273,007 would have turned the game over seven times for a total score of 7,273,007; therefore, this player would earn a place among the top ten finalists. This method was how Imagic knew who would be in the top ten finalists when the contestants submitted the photos to Imagic via snail mail. Unfortunately, the top four players were never sent to Bermuda with a guest to compete in a contest to win a chest of gold worth $10,000 because of the great video game crash of 1983. Imagic eventually became part of Activision.

Atlantis II's value has been rated at $6,000.00 by a few websites, but has sold for as much as $18,000.00 and may well be worth more because there are only ten of them in existence. Until recently it was never officially known how many of these competition carts were produced.