Star Trek: The Rebel Universe looked far better on an ST than on a PC.
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Compare:
http://www.atarimania.com/st/screens/star_trek_the_rebel_uni...
https://www.myabandonware.com/media/screenshots/s/star-trek-...
[edit]
Compare:
http://www.atarimania.com/st/screens/star_trek_the_rebel_uni...
https://www.myabandonware.com/media/screenshots/s/star-trek-...
Although to be fair CGA wasn't intended to be used on monitors. It was intended to be used on smeary composite video sources where you could expand the palette using artifact colors. Even then the graphics were terrible, but you could at least get a green.
It definitely required you to have lost many times before you could complete it though; the galaxy was too large for you to explore fully in the time granted by the mechanics.