It’s now 40 years since gamers began sliding falling blocks around screens to the iconic melody of a Russian folk song. Alexei Pashitnov’s puzzle game quickly gained popularity and was played around the world, particularly when released on the Game Boy in 1989. Today, to play this still highly addictive classic of computer game history, you don’t need a Game Boy to hand, and the game can be started for free with two clicks on tetris.com. The first notes of the Tetris melody provide a little nostalgia while you try to improve on your high score. There are ads, but only for Tetris games and none…