Tetris turns 25 today.

This article says it best:

Tetris die-hards know the feeling: The game makes us stare unblinkingly at the screen for hours. It makes us yell at the inanimate display when we accidentally drop a block one square off. Its Russian folk-song theme worms its way into our ears and lingers all day. It makes us yearn, more than anything, for just one long, vertical piece.

and:

For one, playing the game is an exercise in futility. You can never win. The game is set up so that the blocks fall increasingly faster, until it catches up with you. The goal, then, is the continued pursuit of besting your previous high score. (This is classic addict behavior — “I want my highs to get higher and higher.”)