GC1 and GC2
Moo2 -- But -- just got a new PC with Windows 8, and was using the Moo2 from "GameStop" on Vista with a "DosBox", but since getting my new PC it doesn't work any more. The game comes up and kinda runs but many of the mechanics in it are crippled. I have Moo1 and Moo3 available, but I really dislike them.
WOW (World of Warcraft)
Civ 1 through 5. Not so much of 3 and 4, which I think were very poorly done. 1 and 2 through a DosBox, but now 2 doesn't work on my new PC. Also, I got my current copies of 1 and 2 from GameStop.
Age of Empires 3
Caesar III and IV -- Caesar III worked on my Windows Vista PC, but won't even install on Windows 8
Starcraft (the original version)
Dragons and Dungeons (A box set of the original 8 games) -- in a DosBox. And amazingly, these work better on my Windows 8 than they did on Vista.
OK, so some of these are not properly 4X games, but it shows the lengths I have to go to to entertain myself, and how boring it is to play only one or two games exclusively.
Also, with the experience I have had with my PC upgrade (new machine with Windows 8), I am pleasantly very surprised to find that GC1 installs and runs well on 8. I consider this a BIG testimonial to StarDock.