How Tetris conquered the world, block by block

The concept is simple: from the top of the screen a series of differently-shaped “blocks” fall slowly towards the bottom. The player can turn each block as it falls – making a line into a column, say – or move it sideways, but once it hits the lowest point, it stays. If the blocks fill a line without gaps, they disappear. Otherwise they pile up, giving the player less and less time before they hit the “bottom”.
Simple; but hugely addictive. A quarter of a century later, it has a legitimate claim to being the videogame that has truly conquered the world. — Guardian