"When Ralph Baer invented the home videogame way back in the late '60s, one of the first human interface devices he and his engineering team at Sanders Associates (which just so happened to be a military contractor) devised was a makeshift light-pistol. Not really anything more than a light "detector" with a handle, the pistol was used to select bright white squares against a black background in various test routines. It was then re-engineered to fit inside a toy rifle bought at a local department store, and was finally redesigned one last time as a pump-action shotgun accessory for the first ever videogame console released in 1972, the Magnavox Odyssey. Not only was the console a commercial success, but the high-priced rifle accessory also sold extremely well, shifting around 80,000 units during the console's lifespan."
Staring Down the Barrel