Bill54fish, there were actually two, both from Paragon Software Corporation: MegaTraveller 1: The Zhodani Conspiracy (1989) and MegaTraveller 2: Quest for the Ancients (1991).
In TZC, your goal was to uncover a plot between a megacorporation and the Zhodani. Many (though not all) of the MT rules were used, including a good chunk of the character generation rules and many of the skills. Ground exploration and combat were included, as were starships and trading. Starships in TZC actually added a feature just for the game: starship control programs that could be looted or purchased to enable or improve certain ship functions.
However, only eight of the mainworlds in the Spinward Marches were used (seven in the Regina subsector and Louzy in the Jewell subsector), so travel was somewhat limited. Still, for the limitations of the day I thought it did a pretty good job of realizing as a computer game the feel of the tabletop version of MT.
QftA offered a lot more planets -- basically every mainworld in the Regina, Aramis, Lanth, and Rhylanor subsectors. In fact, in QftA you start on Rhylanor where an Ancient site has started spewing some incomprehensible goo over the whole planet, and your mission is to find a way to stop it before the whole planet is covered. This goes pretty slowly, but it's still a ticking clock.
Most of QftA's systems can be summed up as "the systems from TZC only more so." Pretty much all systems were enhanced -- the chargen in QftA, for example, was implemented with near-perfect fidelity to the official paper version; tabletop GMs could actually use it to create characters for their games. Every star system buzzed with ships; pirates showed up a lot more often; planets were larger; cities had more buildings and inhabitants; and so on. With so many more mainworlds, QftA retained the decent gameplay of TZC while doing a much better job of letting players enjoy the exploration aspect of MT.
Ultimately both games offered the "talk to the good guys, shoot the bad guys, and collect the required keys" gameplay that are the standard model for computer RPGs. That said, both games made this gameplay reasonably entertaining, and (IMO) did about as good a job as could be done given the prevailing technology of bringing the MegaTraveller universe into existence as a computer game. I certainly enjoyed playing both of them (more than once)!
One of these days I'm going to find someone with a 5-1/4" drive and reload my copies of both games onto my current PC. (Though I'll probably need DOSBox to play them. Sigh.) Until then, I'm stuck wondering what a MT game built around the Crysis graphical engine, Bethesda's Radiant AI middleware, and BioWare's multi-character-party system might look like....
Oh, and hello, all!
--Flatfingers