Tennis for Two, which you'll see in this contribution, is considered as the first video game (not computer game!) ever. It is often seen as a predecessor to the famous Pong which was published by Atari about 20 years later.

Tennis for Two was programmed in 1958 as a highly entertaining piece for a visitor's day at Brookhaven National Laboratory, where also the first game for a digital computer, Spacewar!, was created later in 1961.