What do you think?
A daunting array of buttons greeted the aspiring Defender: left, right, hyperspace, smart bomb, and fire. Plus a joystick. The difficulty of the game was legendary, but it only contributed to its immersive quality: when you played Defender you couldn’t spare any attention for the real world.
Your job was to pilot a spaceship that buzzed the surface of a side-scrolling planet and attempted to laser down landers that were busy abducting humans. It was a daunting task: the gameplay had you slipping fluidly around the screen, switching direction as needed, while being swarmed by a terrifying variety of tiny enemies that coalesced out of thin air, though they did explode satisfyingly into fireworks when you hit them, with a thumping basso soundtrack.
In 1981, a year after the original, Williams released a sequel called Stargate. It was even harder.