At any time, the player can engage a hyperspace feature to move to a new and random location on the screen, though in some versions each use has an increasing chance of destroying the ship instead.

A few programs, however, were intended both to showcase the power of the computer they ran on and as entertainment products; these were generally created by undergraduate and graduate students and university employees, such as at the Massachusetts Institute of Technology (MIT), where staff and students were allowed on occasion to develop programs for the TX-0 experimental computer.

[1] These interactive graphical games were created by a community of programmers, many of them students and university employees affiliated with the Tech Model Railroad Club (TMRC), led by Alan Kotok, Peter Samson, and Bob Saunders.

[1][2][3] In September 1961, a Digital Equipment Corporation (DEC) PDP-1 minicomputer was installed in the "kludge room" on the 2nd floor of Building 26, the location of the MIT Electrical Engineering Department.

The PDP-1 was to complement the older TX-0, and like it had a punched tape reader and writer, and additionally accepted input from a panel of switches and could output to a cathode-ray tube (CRT) display.

Over the summer before its arrival a group of students and university employees had been pondering ideas for programs that would demonstrate the new computer's capabilities in a compelling way.

involves two monochrome spaceships called "the needle" and "the wedge", each controlled by a player, attempting to shoot one another while maneuvering on a two-dimensional plane in the gravity well of a star, set against the backdrop of a starfield.

[6] Torpedoes are fired one at a time by flipping a toggle switch on the computer or pressing a button on the control pad, and there is a cooldown period between launches.

[4] Russell had recently finished reading the Lensman series by E. E. "Doc" Smith and thought the stories would make a good basis for the program.

"[5] Other influences cited by fellow programmer Martin Graetz include E. E. Smith's Skylark novels and Japanese pulp fiction tokusatsu films.

Kotok drove to DEC to pick up a tape containing the code, slammed it down in front of Russell, and asked what other excuses he had.

[2][4] Russell, later explaining that "I looked around and I didn't find an excuse, so I had to settle down and do some figuring",[2] started writing the code around the time that the PDP-1's display was installed at the end of December 1961.

[2][11] It took Russell, with assistance from the other programmers—including Bob Saunders and Steve Piner (but not Wiitanen, who had been called up by the United States Army Reserve)—about 200 total hours to write the first version of Spacewar!, or around six weeks to develop the basic game.

[14] Russell had a program with a movable dot before the end of January 1962, and an early operational game with rotatable spaceships by February.

[2] The programming community in the area, including the Hingham Institute and the TMRC, had developed what was later termed the "hacker ethic", whereby all programs were freely shared and modified by other programmers in a collaborative environment without concern for ownership or copyright, which led to a group effort to elaborate on Russell's initial Spacewar!

Additionally, in March 1962, Saunders created gamepads for the game, to counter "Space War Elbow" from sitting hunched over the mainframe toggles.

[2] One feature, having the speed and direction of torpedoes differ slightly with each shot, was added and then removed by Russell after player complaints.

[15] With the added features and changes in place, Russell and the other programmers shifted focus from developing the game to preparing to show it off to others such as at the MIT Science Open House at the end of April 1962.

[2][10][17][18] The group added a time limit, the hyperspace function, and a larger, second screen for viewers at the demonstration, and in May Graetz presented a paper about the game, "SPACEWAR!

[2][19] The demonstration was a success, and the game proved very popular at MIT; the laboratory that hosted the PDP-1 soon banned play except during lunch and after working hours.

[2][20] Visitors such as Frederik Pohl, the editor of Galaxy Science Fiction, enjoyed playing the "lovely game" and wrote that MIT was "borrowing from the science-fiction magazines", with players able to pretend to be Skylark characters.

was reportedly used as a smoke test by DEC technicians on new PDP-1 systems before shipping because it was the only available program that exercised every aspect of the hardware.

was extremely popular in the small programming community in the 1960s and was widely recreated on other minicomputer and mainframe computers of the time before migrating to early microcomputer systems in the 1970s.

[23] Early installations included the PDP-1 at Bolt, Beranek, & Newman, which also recreated the gamepads; an installation by Russell on a PDP-1 at the Artificial Intelligence Laboratory of Stanford University in 1963; and the University of Minnesota, where MIT graduate Albert Kuhfield in 1967–68 recreated the game for the CDC 3100, and submitted a description to Analog Science Fiction and Fact, published in 1971.

on a combined PDP-6/PDP-10 that supported five players, and was the first ever video game tournament, with an account published in the December 7, 1972 issue of Rolling Stone.

in 1977 that ran on the Altair 8800 and other Intel 8080-based microcomputers using an oscilloscope as the graphical display and a lookup table to approximate the calculations for orbits,[29] as well as a three-dimensional variant in 1979 written in Tiny BASIC.

[33] The only working PDP-1s that are known to exist are kept in the Computer History Museum in Mountain View, California, where demonstrations of the machine are held, which include playing Spacewar!.

[36][37] Additionally, in the arcade game Asteroids (1979), designer Ed Logg used elements from Spacewar!, namely the hyperspace button and the shape of the player's ship.

: Dan Edwards, Martin Graetz, Steven Piner, Steve Russell, Peter Samson, Robert Sanders, and Wayne Wiitanen.