If you haven't played this game, then you're missing the foundation of a genre.
Gameplay: It's simple, addictive, fast as you want, and slow as you want. I could forcefully dominate through a huge galaxy with 6 aliens in a few hours, or I could slow down and be more diplomatic with a small galaxy with 2 aliens, and that could go on for weeks.
Sound: Not much to say here, it's 1993! Most games lacked music, this one included, and the sounds, while unique for it's time, still manage to hold up. mostly high-tech beeps and lasers and simple explosions, nothing special.
Graphics: VGA at it's finest, as many colors as they could possibly fit on a screen. The stars on the playing field twinkle with different colors, many different varieties of ships to build. The aliens are unique, and the diplomatic screens were high-quality for it's time.
Bottom Line: Classic, absolute classic. It was an incredible game because it had that special, addictive "hook", and that's missing in most of today's games.