Galaxy Game

The gameplay of Galaxy Game, like Spacewar!, involves two monochrome spaceships called "the needle" and "the wedge" (though their appearances have been modified for the coin-op version) each controlled by a player, attempting to shoot each other 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, 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 there is an increasing probability of the ship exploding with each use.

After deciding to begin work on a coin-operated version of Spacewar, the pair, with assistance from Tuck's family, bought a PDP-11 and started working on a prototype. They spent a total of US$20,000 (equivalent to about $159,000 in 2025) to build a single arcade machine for two players, like the original Spacewar, deciding to price the game at ten cents per play or 25 cents for three games, with the winner of a match given a free game. They used a PDP-11/20 version of the PDP-11 (US$14,000), a Hewlett-Packard 1300A Electrostatic Display (US$3,000), and spent the remainder on the coin acceptors, joysticks, wiring, and casing. Pitts build the computer hardware and handled the programming, while Tuck, a mechanical engineer, designed the enclosing cabinet.

The display adapter for the monitor was built by Ted Panofsky, the coin acceptors were sourced from jukebox manufacturer Rowe International, and the joysticks found at a military surplus store as remainders from B-52 bomber controls. The code for the game was based on a version of Spacewar running on a PDP-10 in the Stanford artificial intelligence lab, but modified with additional features.

The second Galaxy Game prototype remained on display in the Tresidder building until May 1979, when it was removed due to the display processor becoming unreliable. Throughout its time on display, it remained popular, with "ten to twenty people gathered around the machines most Friday and Saturday nights when school was in session." Pitts later claimed that by the time the machine was removed, it had managed to make back the original investment. After its removal, the machine was dismantled, with the computer parts stored in an office and the casing outdoors.

The unit was restored in 1997 with a recreated display processor and put on display for several years in the computer science department at Stanford with two consoles attached for free use by students. Due to issues with space and maintenance, in 2000 it was moved into the Computer History Museum in Mountain View, California, in the displayed storage section. In August 2010, the museum loaned the console to Google to be placed at their headquarters campus at the request of Pitts—who wanted the game to be played as well as displayed—due to a discussion with senior vice president Jonathan Rosenberg, who had been hired as a 13 year old by Tuck and Pitts in the mid-1970s to keep the machine cleaned. It has since returned to the museum as a playable exhibit.