Meh to the overrated Total Annihilation.

Outcast
Freespace 2
Dark Reign
Dark Reign 2
Star Control 2
Heroes of Might and Magic 3
Tyrian 2000

And that is off the top of my head. There's probably many more. I have no idea why GoG hasn't put out a soundtrack for the songs in Ultima 7,8, or 9 (9's Dragon Edition came with a soundtrack) or the incredible soundtrack for the Wing Commander games (I assume EA is being a problem).

No, but after listening to the Hotline Miami soundtrack on Youtube, it would have became a contender if it had the OST as a bonus.

Total Annihilation
Heroes of Might and Magic III
Warlords Battlecry II

I would say Baldur's Gate 2 as well but gog version of soundtrack doesn't have all tracks from Shadows of Amn and none from Throne of Bhaal.

Already have Tropico and just bought the game on GOG for the soundtrack.