Released in 1981, Galaga was a revelation to kids who were used to Space Invaders.
The screen was set up the same way — you control a spaceship that can shoot and slide from side to side — but instead of an orderly block of grey aliens trudging predictably back and forth above you, Galaga sent curving streams of brightly colored ships curling down towards you, looping and spiraling before forming up and commencing to bomb you back to the stone age.
There was a powerfully organic, analog feel to those flight patterns, and it felt like the future of enemy AI. It was.