* ExecutiveMeddling: The original design was a VideoGame/{{Breakout}} clone with the twist that the "bricks" fire back; they were originally people, but the executives vetoed it. They were then changed to airplanes, but they didn't make sense with the way they moved. After seeing ''StarWars'', the developer was inspired to change the enemies to aliens, which were [[WhatMeasureIsANonHuman acceptable to shoot and kill.]] It also justifies their lateral movement patterns, which didn't work with the previous designs.
* KillerApp: The Atari 2600 version
* PortOverdosed: There is a version of ''SpaceInvaders'' for almost every platform ever made, including graphing calculators and wristwatches.
* SerendipityWritesThePlot: The speed increase of the aliens as the game went on was an unintended side effect of the weak processors at the time, but the developers liked it enough to keep it in.