Anyone remember the Freespace series? I think the first one was actually Descent: Freespace, but the second was just Freespace 2.
God that series was great.... nothing be great memories. That was the first series for me that had a real sense of "scale" from the war to save mankind... to the overall futility of the alliance against the Shivans... to the actual physical scale of the capital ships against your one man fighters. Great series I wish they would continue!
I believe Volition published those games. Unfortunately when Freespace 2 came out they were already in their death throes, thus not many copies of FS2 hit retail.
The Space Sim genre has been on life support for the longest time. I get my space sim fix from the X series, specifically X2 - The Threat, X3 - Reunion and X3 - Terran Conflict (got it, but haven't played it). I'm currently re-playing X2 and X3 - Reuion. They are great games, but the learning curve is a bit steep and they will not appeal to everyone since the X series is not a pure space combat sim. It's best thought of as a sandbox space combat and trading simulator. You can pilot fighters, transports and capital ships.