Galaxian

Galaxian is the game between Space Invaders and Galaga, and the step it added was the dive. It was Namco's first real hit and the first arcade game to use a full-colour RGB palette for its sprites.

The formation sits at the top of the screen as in Space Invaders, but instead of marching down it sends individual aliens into swooping attack runs, complete with explosion animations and dive paths that curve back to their slot. That one change turns a static shooting gallery into a rhythm game: you time your fire between dives, and hitting a diving alien scores far more than hitting one sitting still. The flagship alien in each row - the one that carries two escorts - is worth the most, and the entire scoring system is built around shooting it first. Midway and Irem both licensed the board for overseas release, which is why multiple versions exist; the screenshots on this page come from the Irem set. Its 1981 sequel Galaga refined everything here into the game most people remember.

• ▸Aliens dive in swooping runs instead of marching down
• ▸Hitting a diving alien scores far more than a seated one
• ▸The flagship alien, worth the most, carries two escorts
• ▸The first arcade game to use a full RGB colour palette