Pong

Pong is a 70's Arcade game published by Atari and was a big hit at the time of its release. It is one of the earliest video games of all time, and is one of the earliest video games to recieve mainstream popularity.

Gameplay
The basis of this game is that you have to get the ball to the opponent's goal and the opponent must try to do the same for your side. It is basically virtual tennis. It may look boring to modern gamers, but for its time, it was quite entertaining.