Launched in 1989, Tetris was invented by a researcher at the Computer Centre of the USSR Academy of scientists in Moscow and programmed by an 18-year old student at Moscow University.
The game, published by Spectrum Holobyte, was the first commercial computer program to reach the West from the Soviet Union.
A tall empty rectangle in the centre of the screen represents what might be considered a pit or a well. Into this space fall, one at a time, an assortment of seven brightly coloured abstract shapes, all derived from four small squares (like Lego bricks).
The object is to pack the well tightly, leaving as few blank spaces as possible. In addition to being great fun, the game is also instructive: to succeed, the player must learn to plan ahead under pressure, to know where best to place any of the seven shapes at any given time, quickly rotating them to fit.