Nintendo took the falling-block formula and gave it a theme: Dr. Mario (1990) has you dropping two-tone pills to wipe out colored viruses bouncing in a jar.

The thing that separates it from Tetris is that your pieces split. A pill is two halves, and when the tiles beneath one half clear, that half falls on its own and lands somewhere you may not have planned. That single rule turns the board into a chain reaction machine. Set up a stack so that clearing one virus drops a loose half onto a matching color, and the whole column unravels for you. Good players don't clear viruses one at a time; they build a structure and then pull one brick out of it.

Difficulty is set by three dials rather than one: how many viruses start in the jar, how fast the pills fall, and how many colors are in play. That last one matters most. At two colors the game is almost a formality; at three the odds of getting the pill you need collapse and the stack climbs.

Head-to-head is where it lived. Clear two or more virus rows at once and garbage rains into your opponent's jar, which is the mechanic every competitive puzzle game since has borrowed. It also shipped on the Game Boy the same year, with the link cable, which is how a lot of these matches actually happened.

And the music. There are two tracks, "Fever" and "Chill", and every player has an opinion about which one you're supposed to play to. They're permanently lodged in the brain of anyone who touched this game, and "Fever" has been remixed into every Nintendo crossover since.

A puzzle game with Mario's face on it, infinitely replayable, and proof Nintendo could make magic out of the simplest idea.