Tetris - sold over 495 million times.
Or at least this is the number it is possible to track.
Read story"Tennis for Two" is the name of the very first interactive video game and it used an oscilloscope for a screen.

The game was created by American physicist William Higinbotham a.k.a. Willy in 1958.
He discovered how to make the game while reading the instruction manual for a Donner model 30 computer used by the US government. The analogue computer could calculate missile trajectories (or a bouncing ball) with wind resistance.