In addition to the many amazing games already mentioned, I’ll throw in the 1995 gem “Ascendancy” from The Logic Factory. The user interface is a bit rough by modern standards but, for its time, it was a fascinating 4X turn-based strategy game (despite the broken “AI”) with an impressive array of alien races with unique art and music for each. It’s been in-and-out of the “abandonware” classification over the years, so there may not currently be any legitimate way to acquire a copy of the game–which is a real shame for those who might want to experience a nearly 30-year-old game that I think was groundbreaking for its time.