Novalogic Delta Force from 1998 on my Win 7 PC (won't work on my win10 laptop) or Total Air War (F-22 simulator) which was also 1998, and had the absolute best dynamic campaign setup of any flight sim I've ever played and, with a graphics update, would still be spectacular.
I never actually played it in its hay-day, but I play Links 2003. I think this is the oldest game I play.
Always go back to Total Annihilation and have a few games with the girlfriend. It just offers exactly what we look for in an RTS.
Command & Conquer Renegade