The young Russian programmer Aleksej Pajitnov didn't quite know what he was doing when he created a game where falling blocks would be stacked in increasingly rapid tempo. 40 years later, it's one of the world's best-selling computer games.
The game, which was dubbed Tetris, immediately succeeded – first among Pajitnov's colleagues, then the rest of the world. Today, it's one of the world's absolutely best-selling games. In 1993, Tetris became the first computer game in space when Russian cosmonaut Aleksandr Serebrov took his Gameboy with him to the Mir space station.
For a long time, it was considered impossible to get much further than level 29 in the game, but earlier this year, 13-year-old Willis Gibson managed to get all the way to level 157, which is described as the game's "kill screen" – where it crashes.
Pajitnov was impressed, but maintains that it's impossible to crash his game.