He was fascinated by the potential of television to become an interactive medium, not just a passive device, and in 1966 -- while waiting for a friend at a New York City bus terminal -- he scribbled down some notes about a home videogame system. He came up with possible game categories: Action, Puzzle, Instructional and Sports. That same year he got together with some fellow engineers and built a prototype, a system that could move dots around the screen. A later version allowed for multiple games, including one with a light gun. One version even played Pong.
Unfortunately, it was a hard sell. Television companies didn't see the potential in videogaming. And Baer didn't find any takers until Magnavox saw a demonstration of his technology in 1971. They bought rights to all the patents and launched a rudimentary game system in May of 1972: the Magnavox Odyssey. It was the first home console, and with 12 available games, it was way ahead of its time. The high price point ($100) and misconception that it would only work with Magnavox TVs really hurt the system's sales, but Baer's mark was forever stamped on gaming history.
source: www.gamespy.com