A year later, Nintendo bundled it with the Game Boy, and made Tetris synonymous with its new handheld.
In terms of its universal popularity, there's an argument for Tetris being the greatest video game of all time. Certainly, I can think of no other game which is so welcoming to everyone. Christmas 1990, for me, is defined by Tetris; it brought my entire family together.
Those pre-Game Boy versions of the puzzler lack the culturally dubious Russian music and theming that Nintendo slapped on its release. There are no onion domes, or reverse R to be seen. Mirrorsoft's Commodore 64 incarnation - despite having none of the fluid gameplay which would go on to make the Game Boy version one of the biggest games ever - even adopts a vaguely sci-fi look.
Nintendo saw the broad potential of Tetris, and knew that getting it into the hands of everyone was key. "From Russia With Fun" read the box artwork - and even the cover of the Game Boy packaging featured Tetris on the handheld's screen. Unlike Atari's Lynx and Sega's Game Gear, Nintendo wouldn't attempt to sell its system on graphics, but on entertainment. Tetris was as addictive as crack. No wonder they gave away that first hit for free.

Because of Tetris, the Game Boy is the only games console my mother has ever owned.
She'd played on my Atari - I've fond memories of her weaving around on the sofa as she tried to dodge the shots in Space Invaders - but Tetris absolutely got her. It got us all that first Christmas. My Game Boy was passed around from person to person like a newborn baby.
The second anyone stopped playing, and the Game Boy was left alone on a flat surface, somebody else would pick it up. Family members who'd never shown any interest whatsoever in video games would play it. If I recall, as soon as Christmas was over, my mum went out and bought her own.
I've a home video of that Christmas somewhere - it was my eldest daughter's first one, and marked by our neglect of her as we stayed focused on that monochrome screen. In the background of almost every shot you can hear people shouting out that they'd beaten their high score, or "I just got twenty lines!".
The learning curve of Tetris - how you can at first struggle to clear a single line, and within a week be clearing 100+ - still baffles me. You don't feel like you're learning how to get better, but the steady drip drip drip of improvement is what kept us all hooked. That rush as your line score soars into triple digits for the first time, and the tempo ramps up in synch with your pulse...

Tetris was a perfect marriage of content and platform. I'd suggest that there wasn't that flawless symbiosis again until Nintendo released the Wii, and bundled it with Wii Sports.
It felt as if Tetris had been developed in conjunction with the Game Boy - not that it was the product of some Bilbo-esque Russian boffin, working for the Soviet Academy of Sciences.
Arguably, Nintendo got lucky. The Game Boy would've been a hit regardless - its battery life alone guaranteed it victory over its handheld rivals - but Tetris pushed it to another level.
The Game Boy went from being a toy for kids, to being a toy for everyone. Somewhat appropriate for a game developed under a Communist regime.