Russian brain teaser Tetris features a rain of shapes which tumble down a players' screens and it is up to them to reorient each shape to make complete rows. It's one of the most ridiculously addictive games of our time, and since its release in the early '80s it's been ported to just about every gaming platform.
Tetris is a game that's lasted through the ages with not much of anything changing within its original gameplay mechanics. More modern Tetris versions are flashier, but they've still got the same shapes, the same game board, and it still brings out same addictive nature in gamers today.
Top 100 Video Games of All Time #5 - Tetris