Xevious

Xevious is a vertical-scrolling shooter arcade game developed and released by Namco in 1983. In North America, it was published by Atari, Inc. Controlling the Solvalou starship, the player is tasked with wiping out the Xevious forces before they destroy all of mankind. The Solvalou has two weapons at its disposal: an air zapper to destroy flying enemies, and a blaster bomb to destroy ground-stationed enemies. It ran on the Namco Galaga arcade system.

Further info on the cancelled Atari 2600 version:

When Ray Kassar was fired as CEO of Atari in 1983, James Morgan was hired to take his place. Morgan put all projects on hold for 30 days while he reviewed what had been going on during Kassar's leadership. It was originally assumed that Xevious was one of the Atari 2600 titles that were killed off during this time, but recently a nearly complete version of the game was found, proving that it survived at least until early 1984. Unfortunately, the 2600 version along with the 5200 version were eventually cancelled, with the 7800 version being the only one to see the light of day. Had it been finished, the Atari 2600 version of Xevious probably would have been a mainstay in the 2600 library and a big hit, but it appears that Atari wasn’t willing to wait.

A promo box of Xevious was shown at the Winter 1983 CES.