Alexei Paschitnow a russian Coder created 1984 on an Elektronika-60-Computer one of the most simplest and addictivest games of all times..TETRIS.
as mentioned the Idea was and still is simple..7 different types of falling blocks have to be rotated before they fall down, to match a horizontal line. when a horizontal line is filled the blocks fall down one level.
the game ends when one of the blocks reach the top of the screen and none can be placed on top of the last line anymore.
Tetris was released for almost every Console Type,PC´s, on Handhelds and Mobile Phones.