I'm showing my age, but my favorite computer game of all time was Serpentine. It ran on an Apple ][. The personal computer before the term "Personal Computer" was coined.
Supreme Commander is by far my most favorite RTS. IMO the best RTS game out there.
Master of Orion my fav classic game. I sometimes boot up a VM of XP on my Vista64 box just to play it.
Honurable mention to Warcraft 2 and Kali. I had some awesome times back in the 90s with that.
I've spent lots of hours playing Resident Evil 2 on my PC (not on PS)
And I've recently re-re-re-installed TES3:Morrowind on my new build just to see how SMOOOOOOTH it runs.