Defender

Defender is an arcade video game developed and released by Williams Electronics in February 1981. A horizontally scrolling shoot 'em up, the game is set on an unnamed planet where the player must defeat waves of invading aliens while protecting astronauts. Development was led by Eugene Jarvis, a pinball programmer at Williams; Defender was Jarvis' first video game project and drew inspiration from Space Invaders and Asteroids. (wiki)