This is an unauthorized conversion of the 1978 Taito coin-op game Space Invaders for the Atari 2600. Unlike the authorized Atari Space Invaders, this version has all nine rows of invaders without flicker, rather than just six. Also, the sounds are closer to the arcade game. Gameplay is the same - shoot the rows of invaders and avoid their bullets, using your bases as shields and taking out the enemy mothership when it appears.
