Setting the scene
Tetris had already become a global puzzle phenomenon on computers and consoles after Soviet programmer Alexey Pajitnov created it, but handheld gaming still needed a killer app to justify carrying a device everywhere.
What happened
When Nintendo launched the Game Boy in 1989, Tetris shipped in the box in North America and Europe, pairing Henk Rogers's licensed version with a portable screen millions could slip into a pocket.
Why it still matters
Bundling the game with the hardware turned a Soviet puzzle into the defining launch title for handheld gaming and fueled years of Game Boy sales. Memorable detail: licensing fights between Nintendo, Atari, and others had already made Tetris famous before the Game Boy existed.
Background
Licensing battles had already made the puzzle famous.