Bubble Bobble (1988 on the NES, 1986 in arcades) is co-op perfection in a single screen. You and a friend are the bubble dragons Bub and Bob, trapping enemies in bubbles and popping them across 100 increasingly fiendish rooms.

The two-step kill is the entire design. You can't hurt anything directly; you blow a bubble, the enemy gets stuck inside, and then you have a few seconds to jump over and burst it before it escapes angrier than before. That gap turns every screen into a small logistics problem. Do you trap them one at a time and stay safe, or herd four into a corner and pop the lot for a cascade of fruit worth ten times as much?

Bubbles are also the platforms. Bounce on your own bubbles to reach ledges you otherwise can't, which is how most of the higher shelves get cleared and how you escape a floor that has gone bad. Water bubbles carry you downward in a flood that kills anything in the current, lightning bubbles fire a bolt, and the letters spelling EXTEND grant a free life when you collect all six.

Dawdle and the game sends Baron von Blubba, an invincible skull that chases you until the screen is clear. There is no fighting it. You clear the room or you die.

And famously, the true ending only unlocks in two-player mode. Finish alone and you're told, flatly, to come back with a friend. Get there together and you learn Bub and Bob are cursed humans, which is the sort of plot a 1986 arcade game had no obligation to bother with.

That one looping theme burrows into your skull and never leaves. Pure, joyful, endlessly replayable. One of the great couch co-op games of the era.