It was called "Pong", which is where we get the word "pong" to refer to a simple, basic game.  In "Pong" the object was to move a paddle around to bounce a ball back to your opponent.  Here's a picture of the game:
assitant
It was Space Invaders.
assistant
What was the first video game that was for sale?
user
OK, I looked this up and the first retail sale was in Japan.  They sold the first game in September 1976.
assistant
What game was it?
user