Tetris, one of the most renowned and addictive creations in the brief history of video games, turns 25 this week.

Creator Alexey Pajitnov at the Moscow Academy of Science programmed the iconic falling-block game in June 1984 for a Soviet computer system called Electronika, according to the San Francisco Chronicle. The Reuters news agency cites June 6 as the date that the first playable version of the game was born.

"The program wasn't complicated," Pajitnov told the U.K.'s Guardian newspaper. "There was no scoring, no levels. But I started playing and I couldn't stop. That was it."

The deceptively simple game, which did eventually come to include scoring and levels, is an ever accelerating test of spatial relations and quick reflexes. Tetris went on to sell millions of copies, becoming a staple of the original eight-bit Nintendo Entertainment System and its handheld companion, the Game Boy. In the process, the game infiltrated the minds of many gamers, who found themselves imagining how everyday objects might fit together or dreaming of Tetris shapes.

According to the Chronicle, after creating Tetris, Pajitnov "entered the game into a computer competition in a nearby city, where it placed second. There was no first place, he was told."

"I didn't understand it either," Pajitnov told the newspaper, citing the frequent oddities of the then-communist nation. "I was just informed my game got a very good score."

Photograph of Pajitnov at a 2007 conference: Sklathill on Flickr