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.
The sources are available in sources.zip.
The older Java version is in a subdirectory called "java".
The "a", "d", "s", "w" keys control one of the spaceships. The "j", "l", "k", "i" keys control the other. The controls are spin one way, spin the other, thrust, and fire.