Steve Russell appears remotely from the Computer History Museum, beside the last working PDP-1.
Computers were not popular in 1961. The state-of-the-art at the time was the PDP-1, a $120,000 dollar cabinet that was twice the size of a refrigerator and sounded like a blender every time you turned it on. The community was mostly found at universities, where fledgling computer scientists were faced with a problem: how could they get people to use the damn thing? They wanted repeat users, developing and employing skills — and simple spirograph tools weren't going to get them there. What they needed was a game.
The result was Spacewar!, one of 21 games currently on display at The Museum of the Moving Image in New York. This weekend, two of the creators, Peter Samson and Steve Russell, gave a talk at the museum about how the game was made.
"We had a thousand hours of playtime to get it right," said Samson "It was open source because we didn't have any choice. You couldn't copyright software in those days."
Since most of the players were programmers, they quickly got to work on new versions
The game pits two spaceships against each other, both orbiting a central star. The developers borrowed the orbit mechanic from Marvin Minsky's Minskytron, a non-interactive demo that showed off geometric interactions, and the star background was lifted from Samson’s "Expensive Planetarium" software. But the interaction model was all new. Just getting the orbit to respond to player actions in real time was a challenge, given the limited processor power, but Russell credited MIT colleague Dan Edwards with finding a way. At the time, there still wasn't enough computing power to apply gravity to the ships' projectile weapons, Russell said, "so we decided they were photon torpedoes, unaffected by gravity."
The initial version of the game was just two players and minimal graphics, but other versions soon popped up. In the summer of 1962 (still twelve years before Atari), Samson unveiled a second version with explosion graphics and scoring. Since most of the players were programmers, they quickly got to work on new versions, adding space mines and strange inertial effects. Other players learned the workings of the PDP-1 just to make their own mods. Soon, there was a version with invisible ships (known as Minnesota Spacewar!), another that showed the view from each ship's cockpit. At Harvard, Ivan Sutherland built a version played on a VR headset, an early precursor to the Oculus Rift. In a landmark Rolling Stone piece from 1974, Stewart Brand describes an internal battle within IBM to let employees play Spacewar! on company time. The bosses held their ground for a few months, but in the end, the game was too popular to keep out.
"50 years old, with no outstanding user complaints."
The version that's on display at the museum now is the one Samson unveiled in '62 with scoring and a two-player limit, but it's far from definitive, and the quick spread of the game was an early example of open-source mod communities in action. Both Samson and Russell would have other breakthroughs — Samson at Autodesk; Russell working on the Lisp interpreter — but neither had much interest in computer games. Spacewar! is still their most popular work. As Russell put it, the game is "50 years old, with no outstanding user complaints, no catastrophic crashes, and it's still available." A pretty good record, all things considered.