SPACEWAR!
Two-player space combat · Outfly, outshoot, survive.Two players on one keyboard. Use brief thrusts to establish an orbit. Hold fire for repeated shots. Hyperspace has a recharge period and growing re-entry risk. Shoot starts local play · P: pause · R: reset.
Operator controls
Switches are the original PDP-1 sense switches. With switch 5 off, entering the star sends a ship to the opposite corner. Finite matches add rounds to break ties. Changing match length resets the match.
Historical program and fidelity
This file runs the preserved Spacewar! 3.1 paper tape in a PDP-1 CPU emulator. The original instructions control movement, gravity, random numbers, fuel, torpedoes, collisions, hyperspace, ship outlines, the Expensive Planetarium and scoring. The tape and gameplay constants are unmodified. Timing follows emulated instruction and display-I/O costs, rather than a fixed game frame rate.
The original program has no universal 30-second round timer. Fuel is finite; its depletion follows the program, without an added balance adjustment. Keyboard/touch controls, supply readouts, Galactic Credits and the cosmetic shop are modern additions. Colors do not change the original game rules. The Type 30 display’s P7 phosphor is simulated; a browser cannot reproduce the physical CRT exactly.
Historical emulator and documentation · 1962 source listing
Spacewar! was conceived in 1961 by Martin Graetz, Stephen Russell, and Wayne Wiitanen. It was first realized on the PDP-1 in 1962 by Stephen Russell, Peter Samson, Dan Edwards, and Martin Graetz, together with Alan Kotok, Steve Piner, and Robert A Saunders. Spacewar! is in the public domain, but this credit paragraph must accompany all distributed versions of the program.
PDP-1 CPU, paper-tape reader and CRT simulation: Norbert Landsteiner, mass:werk (2012–2022), based on the CPU emulator by Barry Silverman, Brian Silverman and Vadim Gerasimov (2012). Their original GUI is not included. This standalone integration supplies the browser controls and readouts.