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 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, 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. Gameplay Space Travel is a spaceflight simulation video game, presented in a two-dimensional top-down view, with monochrome graphics consisting of white lines on a black background. In it, the player controls a spaceship as it flies through a representation of the Solar System. The game has no specific objectives, other than to attempt to land on the various planets and moons of the system. The planets and most of the moons in the Solar System are represented to scale both in size and distance from each other, though the orbits are simplified to be circles. To land on a body, the player's ship must cross the line representing the surface while moving at a low enough speed. The player is able to control the ship to go forwards and backwards and turn. The ship moves at a constant level of acceleration relative to the scale of the screen, which the player can control; scaling the screen up high enough allows the player to travel across the Solar System in seconds, though they risk overshooting their target and becoming unable to find the Solar System again, and scaling down allows the player to be moving slowly enough to land. The ship is always in the center of the screen, facing the top; turning the ship