Spacewar was not the first computer game. From the very beginning, programmers were attracted to games that could be played on the computer. A number had attempted chess programs in the ’50s and even earlier. Konrad Zuse, who designed the first computer programming language, used that language in 1945 to write the first chess-playing program. A few years later Claude Shannon wrote a chess program, as did Alan Turing.

Spacewar, however, was a departure from such programs, which essentially performed a calculation and presented you with a move, which you could respond to now, in 20 minutes, or tomorrow. Spacewar was fully interactive. You controlled a spaceship and your human opponent controlled a spaceship, and you went at each other with guns blazing. The action didn’t stop until one of you disappeared in a ball of fire. This was a much richer form of interaction than any chess program, and it would have a huge impact on computers and computer games.

It all started with a desire by hackers Wayne Witanen, Martin Graetz, and Stephen Russell to show off MIT’s new PDP-1 computer at the school’s annual open house. Most obviously they needed some impressive movement on the computer screen to wow the technically illiterate, but they wanted more. Under the spell of E. E. Smith’s Lensman science-fiction novels, they conceived the ultimate demonstration program: Spacewar! Russell wrote the basic program and other hackers joined in, contributing features to the game. At a time when demonstration programs might have names like Bouncing Ball or Mouse in a Maze, Spacewar was a huge hit.

The creators briefly considered marketing the game, but decided instead to give it away. Throughout the ’60s it spread from university to university, developing a cult following of hackers who added their own modifications, creating local versions. One student at the University of Utah, Nolan Bushnell, was so impressed by the game that he later created a coin-operated version called Computer Space, the first game of the company that would become Atari.

Computer Space flopped. According to Bushnell, the game that had been so addictive on campuses across the country was too complex for your typical beer-drinking bar patron. Bushnell didn’t give up, though, and the company’s second game did much better. It was called Pong.