A pretty bad arcade game made by Sega. A Laserdisc game, it was Sega's first so called "Hologram" game, where graphics that have had faint reflective shadows applied under them are projected onto a hemispherical mirror, which makes them appear to float freely in space.
The plot: you are a cowboy who has been brought forward in time by a very 80s-looking princess who needs you to save her time. You do this by pressing a button or moving the joystick in the direction you are told. This automatically makes it of the same complexity of Dragon's Lair (one of a very few Laserdisc games that are actually fun to play), but extremely easy, since the solutions to the puzzles are almost always given to you.
Time Traveller was a gimmick game that, even though it was almost complete crap, has managed to gross 18 million dollars to date, almost all of it by suckers who are entranced by smoke and mirrors.
A good jumping-off point for learning more about Time Traveller (and the only other Hologram game, Holosseum) is the System 16 web site, specifically http://www.system16.com/sega/hrdw_laser.html#tt .