since you like many genres i will just point out the games from the promotion i know and i think stood the test of time and are still not only good, but great:
Descent:
Didnt play 2 or 3, but the first one was something else, you should have a good joystick or a gamepad with two analogue sticks to enjoy it, since you have to navigate in 3D like in no other game. Its action packed and navigating is fun.
Fallout 1+2:
Those games are what i would describe as "true" rpgs. You can do pretty much what you want, but the world isnt wooden like Morrowind is for me for example. There is one quest for example where you have to free some hostages from a gang. Assuming the corresponding skills are high enough you can try to intimidate them, challenge the boss for a fair fight, give them something in return, kill them all, or even become a member. Or you just ignore the quest or whatever you want. Not all quests are THAT detailed, but when a solution makes sense there is a high chance it is there.
Freespace 1+2:
Great games, and if you dont need that much of a cinematic feeling (i am looking at you Wing Commander) they are argueably the best mission based space action games out there. Also there is an easy to install mod so that you can play the games with graphics that look more like todays standard. That doesnt mean the default graphics hurt, its just that the community is great and active, there is even a giant Babylon 5 mod among other things.