Not mentioned yet:
I am very fond of Rise of Nations, the RTS that actually made you feel you were building an actual empire. Lots of flavor with several meaningful and thematically appropriate bonuses and unique units (not that common at the time), a deeper diplomacy system than I had previously seen in real-time games, and perfectly balanced so you could choose your starting and end time era. Many mechanics more traditionally associated with turn-based (in other words, Civilization, where the designer of RoN came from) were successfully adopted (dynamic borders, influence radius of cities, attrition, special resources and Wonders providing bonuses, assimilation of conquered cities instead of razing everything to the ground, selection of government types, capital cities). It's unfortunately not on GOG.
Another one that is available on GOG: Sid Meier's Colonization. Even despite its age, the mechanics still feel fresh, even better than the remake. Extremely immersive, with a unique economic system based on production of raw goods, manufacture of more valuable ones, and trade, a whole New World to explore and treasures to find, quite complex diplomacy for an early 90s game (and still satisfying nowadays), some touches of humor and an end-game boss to beat and gain your liberty.
Post edited August 14, 2019 by ConsulCaesar