Lightspeed (1990)

Although unplayably dated at this point, Lightspeed still holds strong as one of my favorite space combat and exploration simulators of all time. Earth has been polluted to the brink of utter destruction, and you have been sent out in your massive colony / warship to search out a habitable world. Humanity being an extremely picky species, the hunt is difficult; you'll come across countless duds before finding the only spot in the universe capable of sustaining your kind. Even after finding it, you'll then have to scavenge neighboring worlds for enough resources to settle down comfortably. Doing this will require you to cajole, trick, threaten, or smash the competing alien races into compliance, each of which have their own extremely well-fleshed out sci-fi quirks, tropes, and diplomatic options. The graphics may be painful, the ship combat clunky, and the scope of the universe a little cramped by modern standards, but this is still a solid classic worth hunting down if you feel like going retro for a bit.