Played on release and have a pretty bad memory but from what I do remember there was a great sense of exploration and mystery. No real hand holding and it required you to plan a bit. I really liked it. I bet it looks super dated now so I don't blame you. There's also the fact we had a limited selection of games back then, at least to compare to in a similar vein.
You know when you go to agraprom for the first time and have to go under ground woth the controler at the end, I turned back just before him but the map is still marked so I just went over ground and got in through a brutal fire fight. After that it would never trigger the next thing to go meet doc or whoever it was I made it to the PowerPlant without the decoder thing.
For years I never knew the ending wasn't just the monolith