was installed at the end of 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 total hours to write the first version of Spacewar!, or around six weeks to develop the basic game. It was written in the PDP-1's assembly language. Russell had a program with a movable dot before the end of 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 PGM-11 Redstone rocket. That early version also contained a randomly generated background star field, initially added by Russell because a blank background made it difficult to tell the relative motion of the two spaceships at slow speeds. The programming community in the area, including the Hingham Institute and the TMRC, had developed what was later termed the "hacker ethic", whereby all programs were freely shared and modified by other programmers in a collaborative environment without concern for ownership or copyright, which led to a group effort to elaborate on Russell's initial Spacewar! game. Consequently, since the inaccuracy and lack of realism in the starfield annoyed TMRC member Peter Samson, he wrote a program based on real star charts that scrolled slowly through the night sky, including every star in a band between 22.5° N and 22.5° S down to the fifth magnitude, displayed at their relative brightness. The program was called "Expensive Planetarium"—referring to the high price of the PDP-1 computer compared to an analog planetarium, as part of the series of "expensive" programs like Piner's Expensive Typewriter—and was quickly incorporated into the game in March by Russell, who served as the collator of the primary version of the game. 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