Tetris is a popular "falling-blocks puzzle" single-player computer game originally developed in 1985/86.
The object of the game is to manipulate "tetraminoes" (composed of four square blocks each) by moving each one sideways and rotating it by 90 degree. While shapes are falling your job is to "fill" a horizontal line of blocks without gaps - when this happens the line dissapears. As the game continues the falling speed of the tetraminoes increases.
