What Was the First Commercial Video Game? Computer Space (1971)

The answer depends on the definition of "commercial":

First Video Game (Non-Commercial)

"Tennis for Two" (1958) by William Higinbotham. Playable by two on an oscilloscope, created purely for entertainment. It was a demo, never sold.

First Commercially Sold Video Game

"Computer Space" (1971) by Nolan Bushnell and Ted Dabney. Based on "Spacewar!", it was the first arcade game marketed to the public.

Note: "Pong" (1972) was the first commercially successful arcade game, but "Computer Space" predates it as the first sold.