In 1992 Microprose released Task Force 1942 for DOS. It was a WWII naval sim. I liked it for the ability to run historic naval battles and make new choices and to see how different ships matched up.
What if someone published a space sim which had the ability to composed battles in space with real physics and the ability to have battles between not only fleets but two ships or any number in between? Also it should include the ability to build ships, upgrade weapons, sensors, armor, electronic warfare systems, and all that stuff. Of course, time compression would be a desirable feature.
If anyone is familiar with the David Weber series of novels in the Honorverse ("On Basilisk Station" was the first), something like his concept of space battle in normal space would be interesting to me.
The choice of how the graphics would be rendered would be critical. Naval engagements occurred from a few hundred yards to 40,000 yards. In a space sim combat ranges would be from a few kilometers to millions of kilometers.