Atlantis

Atlantis is a game released for the Atari 2600, the Intellivision, and the Odyssey 2. It was followed on the 2600 by Cosmic Ark.

Gameplay
The lost city of Atlantis is under attack! Wave after wave of Gorgon vessels are approaching, each armed with weapons capable of destroying a part of the city. You are in charge of the command posts at the edges of the city and need to defend it from the invaders. The various gorgon craft will keep flying by on the screen in varying numbers and in different flight patterns. At first they fly high in the sky but then progressively lower. If an enemy makes it low enough before you destroy it, it will use it's weapons and destroy one of the buildings in Atlantis. As you progress in the game, the enemy craft will keep increasing in speed. The game ends when all remaining buildings in the city have been destroyed.

The Intellivision version has the additional challenge of both day and night attacks where the enemies can only be seen through panning light beams. The player can also enter into a ship and take on the enemies directly.

Scoring
Atari 2600 Version:

During a wave:
 * Large Gorgon Vessel—100 points using Command Post shots, 200 points for using Sentry Post shots
 * Gorgon Bandit Bomber—1000 points using Command Post shots, 2000 points for using Sentry Post shots

At the end of a wave:
 * Untouched landmark of Atlantis—500 points