1. Yars' Revenge
But if it's weird sci-fi you want, Yars' Revenge is the pinnacle. It's a game about a mutant space insect that evolved from Earth houseflies over thousands of years, in which you played that fly. Your enemy was a base that slid up and down the right side of the screen behind a barrier that could be chipped away gradually by missiles or eaten in greedy lumps in a grotesque, insectile move. Meanwhile, an enemy missile tracked you slowly and unerringly and could only be avoided by backing off to the field of rainbow static that hovered mid-screen. On the left a cannon that could destroy the base appeared, but it would also kill you if you didn't dodge in time.
Yars' Revenge is a strange dance, approaching your opponents to chip away their defences then buzzing off to avoid them. After repeating this a few times you create an opening then fire the cannon, spinning to safety and watching the fireworks.
All this is accompanied by a low droning sound, a hum that only goes away in the final explosive moment when the screen fills with glitchy, rolling color that spins and tightens into a cylinder. There's no danger during this moment, though there is a flickering line called "The Ghost of Yars" that can be approached to trigger an easter egg of the designer's initials. It's a moment of celebration during which Yars' Revenge lets you continue to play, and though it flashes the score at you afterward – the only time it does, distracting numbers otherwise absent from its clean playscreen – the real reward is just the moment of oddity it barrages you with.
Yars' Revenge was a strange game, but a perfectly paced one, and rather than being limited by the platform it used the Atari 2600's flickery, blocky graphics and catalog of bizarre electronic noises to their fullest.