7. Tetris - 70 million
Tetris is one of the most addictive games known to man, as the sales figures show and the fact it's available on nearly every console and home computer on the market. You can also find the puzzler on mobile phones, calculators, media players and PDFs.
The game was designed and programmed by Alexey Pajitnov in 1985 for the Dorodnicyn Computing Centre of the Academy of Science of the USSR.