PLATO Empire was a direct ancestor to Netrek. PLATO was a system designed in 1968 at the University of Illinois at Urbana-Champaign to be a time-sharing based computer-aided education system.
Of course, the best thing to do was play games on its 512x512 pixel gas plasma display, which was touch sensitive (no mouse required!!).
The goal of the game was simple: conquer the galaxy. You could play as one of four empires: Federation, Romulan, Orion, or Kazari (which were really Klingons, but re-named to avoid legal trouble; the name was changed to Klingon in 1991.)
The galaxy consisted of 25 planets, and each race received 3 of them, with 50 armies on each. Using spaceships, a player would transport his armies to enemy or neutral planets, in an attempt to attain superiority over the entire galaxy. In general, it was best to play the Orion race because, while weaker, their ships were the fastest.
The game required fast thinking (you had to compute angles for phaser fire in your head for instance), and often produced heated emotions. In those days, players were often playing on terminals in the same room and many apocryphal and archetypal stories exist about physical fights that arose from the electronic ones.
In the early 1980s, many PLATO Empire addicts began writing similar programs for other, more popular, types of computer systems, such as VAX/VMS and UNIX based systems. These programs eventually evolved into what is now known as Netrek.
Information contained here adapted from the history of Netrek FAQ, http://www.ecst.csuchico.edu/~netrek/history/History.html