SPACEWAR! is a space combat video game developed in 1962 by Steve Russell , in collaboration with Martin Graetz and Wayne Wiitanen, and programmed by Russell with assistance from others including Bob Saunders and Steve Piner. It was written for the newly installed DEC PDP-1 at the Massachusetts Institute of Technology . After its initial creation, Spacewar was expanded further by other students and employees of universities in the area, including Dan Edwards and Peter Samson . It was also spread to many of the few dozen, primarily academic, installations of the PDP-1 computer, making Spacewar the first known video game to be played at multiple computer installations.
The game features two spaceships, "the needle" and "the wedge", engaged in a dogfight while maneuvering in the gravity well of a star. Both ships are controlled by human players. Each ship has limited fuel for maneuvering and a limited number of torpedoes, and the ships follow Newtonian physics , remaining in motion even when the player is not accelerating. Flying near the star to provide a gravity assist was a common tactic. Ships are destroyed when hit with a torpedo or colliding with the star. At any time, the player can engage a hyperspace feature to move to a new, random location on the screen, though each use has an increasing chance of destroying the ship instead. The game was initially controlled with switches on the PDP-1, though Alan Kotok and Bob Saunders built an early gamepad to reduce the difficulty and awkwardness of controlling the game.
Spacewar is one of the most important and influential games in the
early history of video games . It was extremely popular in the small
programming community in the 1960s and was widely ported to other
computer systems at the time. It has also been recreated in more
modern programming languages for
PDP-1 emulators . It directly
inspired many other electronic games, such as the first commercial
arcade games ,
Galaxy Game and
Computer Space (1971), and later games
such as Asteroids (1979). In 2007, Spacewar was named to a list of the
ten most important video games of all time, which formed the start of
the game canon at the
Library of Congress
* 1 Background * 2 Gameplay * 3 Development * 4 Legacy * 5 Notes * 6 References * 7 External links
Steve Russell , designer and main programmer of the initial version of Spacewar, in 2007
During the 1950s, various computer games were created in the context of academic computer and programming research and for demonstrations of computing power, especially after the introduction later in the decade of smaller and faster computers on which programs could be created and run in real time as opposed to being executed in batches. A few programs, however, while used to showcase the power of the computer they ran on were also intended 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 they were allowed on occasion to develop programs for the TX-0 experimental computer. 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. The games included Tic-Tac-Toe, which used a light pen to play a simple game of noughts and crosses against the computer, and Mouse in the Maze, which used a light pen to set up a maze of walls for a virtual mouse to traverse.
In the fall of 1961, a
Digital Equipment Corporation (DEC) PDP-1
minicomputer was installed in the "kludge room" of the MIT Electrical
Engineering Department to complement the older TX-0, and even before
its arrival a group of students and university employees had been
brainstorming ideas for programs that would demonstrate the new
computer's capabilities in a compelling way. Three of them—Steve
Russell , then an employee at
Harvard University and a former research
assistant at MIT; Martin Graetz, a research assistant and former
student at MIT; and Wayne Wiitanen, a research assistant at Harvard
and former employee and student at MIT—referring to their
collaboration as the "Hingham Institute" as Graetz and Wiitanen were
living in a tenement building on Hingham Street in Cambridge,
Massachusetts , came up with the idea for Spacewar. "We had this
brand new PDP-1", Steve Russell told
Recreation of Spacewar in Java
The gameplay of Spacewar 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. The ships fire torpedoes which are not affected by the gravitational pull of the star. The ships have a limited number of torpedoes and a limited supply of fuel, which is used when the player fires his thrusters. 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. The ships follow Newtonian physics , remaining in motion even when the player is not accelerating, though the ships can rotate at a constant rate without inertia.
Each player controls one of the ships and must attempt to shoot down the other ship while avoiding a collision with the star. Flying near the star can provide a gravity assist to the player at the risk of misjudging the trajectory and falling into the star. If a ship moves past one edge of the screen, it reappears on the other side in a wraparound effect. A hyperspace feature, or "panic button", can be used as a last-ditch means to evade enemy torpedoes by moving the player's ship to another location on the screen after disappearing for a few seconds, but the reentry from hyperspace occurs at a random location, and in some versions there is an increasing probability of the ship exploding with each use.
Player controls include clockwise and counterclockwise rotation, forward thrust, firing torpedoes, and hyperspace. Initially these were controlled using the front-panel test switches on the PDP-1 minicomputer, with four switches for each player, but these proved to be awkward to use and wore out quickly under normal gameplay, as well as causing players to accidentally flip the computer's control and power switches. The location of the switches also left one player off to one side of the CRT display due to the limited space in front of the computer, which left them at a disadvantage. To alleviate these problems, Kotok and Saunders created a detached control device, essentially an early gamepad . The gamepad had a switch for turning left or right, another for forward thrust or hyperspace, and a torpedo launch button. The button was silent, so that the opposing player would not have a warning that the player was attempting to fire a torpedo during a cooldown period.
In the fall of 1961 while brainstorming ideas for a program for the PDP-1, Russell had just finished reading the Lensman series by E. E. "Doc" Smith and thought the stories would make a good basis for the program. "His heroes had a strong tendency to get pursued by the villain across the galaxy and have to invent their way out of their problem while they were being pursued. That sort of action was the thing that suggested Spacewar. He had some very glowing descriptions of spaceship encounters and space fleet maneuvers." Other influences cited by fellow programmer Martin Graetz include E.E. Smith's Skylark novels and Japanese pulp fiction tokusatsu movies .
For the first few months after its installation, the PDP-1 programming community at MIT focused on simpler programs to work out how to create software for the computer. The community had heard of the Spacewar concept, however, and understood that Russell would spearhead the development of it. When members of the community began to feel the time was right to start work on the game, Russell, nicknamed "Slug" because of his tendency to procrastinate, began providing various excuses as to why he could not start programming the game. One of these was the lack of a trigonometric function routine needed to calculate the trajectories of the spacecraft. This prompted Alan Kotok of TMRC to call DEC, who informed him that they had such a routine already written. 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. Russell, later explaining that "I looked around and I didn't find an excuse, so I had to settle down and do some figuring," started writing the code in December 1961. The game was developed to meet three precepts Russell, Graetz, and Wiitanen had developed for creating a program that functioned equally well as an entertainment experience for the players and as a demonstration for spectators: to use as much of the computer's resources as possible, to be consistently interesting and therefore have every run be different, and to be entertaining and therefore a game. 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 man-hours to write the first version of Spacewar, around six weeks to develop the basic game. Excerpt from the Expensive Planetarium star charts
Russell had a program with a movable dot by January 1962, and an
early operational game with rotatable spaceships by February. The two
spaceships were designed to evoke the curvy spaceship from Buck Rogers
stories and the
The initial version of the game also did not include the central star gravity well or the hyperspace feature; they were written by MIT graduate student and TMRC member Dan Edwards and Graetz respectively to add elements of strategy to what initially was a shooter game of pure reflexes. The initial version of the hyperspace function was limited to three jumps, but carried no risk save possibly re-entering the game in a dangerous position; later versions removed the limit but added the increasing risk of destroying the ship instead of moving it. Additionally during this development period, Kotok and Saunders created the gamepads for the game. The game was a multiplayer-only game because the computer had no resources left over to handle controlling the other ship. Similarly, other proposed additions to the game such as a more refined explosion display upon the destruction of a spaceship and having the torpedoes also be affected by gravity had to be abandoned as there were not enough computer resources to handle them while smoothly running the game. With the added features and changes, Spacewar was essentially complete by late April 1962, and 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 in May. The group added a time limit, as well as a larger, second screen for viewers at the demonstration, and that same month Graetz presented a paper about the game, "SPACEWAR! Real-Time Capability of the PDP-1", at the first meeting of the Digital Equipment Computer Users\' Society . 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.
Beginning in the summer of 1962 and continuing over the next few years, members of the PDP-1 programming community at MIT, including Russell and the other Hingham Institute members, began to spread out to other schools and employers such as Stanford University and DEC, and as they did they spread the game to other universities and institutions with a PDP-1 computer. As a result, Spacewar was perhaps the first video game to be available outside a single research institute. Over the next decade, programmers at these other institutions began coding their own variants, including features such as allowing more ships and players at once, replacing the hyperspace feature with a cloaking device , space mines, and even a first-person perspective version played on two screens that simulates each pilot's view out of the cockpit. Some of these Spacewar installations also replicated Kotok and Saunders' gamepad. According to a second-hand account heard by Russell while working at DEC, Spacewar 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. Although the game was widespread for the era, it was still very limited in its direct reach: the PDP-1 was priced at US$120,000 and only 55 were ever sold, most without a monitor and many of the remainder to secure military locations or research labs with no free computer time, which prevented the original Spacewar from reaching beyond a narrow, academic audience. Though some later DEC models, such as the PDP-6 , came with Spacewar pre-loaded , the audience for the game remained very limited; the PDP-6, for example, sold only 23 units.
Two users playing Spacewar on a PDP-12 at the Vintage Computer Festival
Spacewar 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. Early computer scientist
Alan Kay noted in 1972 that
"the game of Spacewar blossoms spontaneously wherever there is a
graphics display connected to a computer," and Graetz recalled in 1981
that as the game initially spread it could be found on "just about any
research computer that had a programmable CRT". The majority of this
spread took place several years after the initial development of the
game; while there are early anecdotes of players and game variants at
a handful of locations, primarily near MIT and Stanford, it was only
after 1967 that computers hooked up to monitors or terminals capable
of playing Spacewar began to proliferate, allowing the game to reach a
wider audience and influence later video game designers—by 1971, it
is estimated that there were over 1000 computers with monitors, rather
than a few dozen. It is around this time that the majority of the
game variants were created for various computer systems, such as later
PDP systems, and in 1972 the game was well-known enough in the
programming community that
In the early 1970s, Spacewar migrated from large computer systems to
a commercial setting as it formed the basis for the first two
coin-operated video games. While playing Spacewar at Stanford sometime
between 1966 and 1969, college student Hugh Tuck remarked that a
coin-operated version of the game would be very successful. While the
high price of a minicomputer prevented such a game from being feasible
then, in 1971 Tuck and Bill Pitts created a prototype coin-operated
Galaxy Game , with a US$20,000 PDP-11. Around the same
time, a second prototype coin-operated game based on Spacewar,
Computer Space , was developed by
Byte magazine published an assembly language version of Spacewar 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 for orbits, as well as a three-dimensional variant in
1979 written in
Tiny BASIC . More modern recreations of the game for
computers have been made as well. An emulated version of the original
game, based on the original source code made publicly available by
Martin Graetz and running in a
In addition to Galaxy Game and Computer Space, numerous other games have been directly inspired by Spacewar. These include Orbitwar (1974, PLATO network computers), Space Wars (1977, arcade), and Space War (1978, Atari 2600 ). Additionally, in Asteroids (1979), designer Ed Logg used elements from Spacewar, namely the hyperspace button and the shape of the player's ship. Products as late as the 1990 computer game Star Control drew direct inspiration from Spacewar. Russell has been quoted as saying that the aspect of the game that he was most pleased with was the number of other programmers it inspired to write their own games without feeling restricted to using Russell's own code or design.
On March 12, 2007,
The New York Times reported that Spacewar was
named to a list of the ten most important video games of all time, the
so-called game canon , which were proposed to be archived in the
Library of Congress
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