Two terminals are hard-wired together. Per Bill Pitts, with assistance by Ted Panofsky: The Galaxy game was probably the first commercial computer game built. It was installed in the Tresidder Union Coffee House (Stanford University) from 1971 to 1978. A single PDP-11 minicomputer is used to drive two separate game screens with two players each. Galaxy is a reprogrammed version of SpaceWar!, which was conceived in 1961 by Martin Graetz, Stephen Russell, and Wayne Witanen and first realized on the PDP-1 at MIT in 1962 by Stephen Russell, Peter Samson, Dan Edwards, and Martin Graetz, together with Alan Kotok, Steve Piner, and Robert A. Saunders using PDP-1 assembly language. It became very popular at most artificial intelligence research centers and is now available in a simulated version on the web: http://lcs.www.media.mit.edu/groups/el/projects/spacewar/. [Ed.: this url is non-functioning.] The original version used 4 keyboard keys to control each of the two spaceships: spin one way, spin the other, thrust and fire. Solar gravity will cause the ships to destruct if no action is taken. The Stanford [University] version added three types of space: no gravity, anti-gravity, and uncharted space.