Space Travel is an early video game developed by Ken Thompson in 1969 that simulates travel in the solar system. The player flies their ship around a two-dimensional scale model of the solar system with no objectives other than to attempt to land on various planets and moons. The player can move and turn the ship, and adjust the overall speed by adjusting the scale of the simulation. The ship is affected by the single strongest gravitational pull of the astronomical bodies.

The rise of Unix

The game was developed at Bell Labs before the rise of the commercial video game industry in the early history of video games, and was ported during 1969 from the Multics operating system to the GECOS operating system on the GE 635 computer, and then to the PDP-7 computer. As a part of porting the game to the PDP-7 (picture), Thompson developed his own operating system, which later formed the core of the Unix operating system.

Space Travel never spread beyond Bell Labs or had an effect on future games, leaving its primary legacy as part of the original push for the development of Unix.

Source: Wikipedia