Megalomania!
I think that was my first RTS... your resource was your population, it increased naturally unless you allocated them to research or army.... played the demo on Atari ST and then bought it on the megadrive (genisis).
That was a few years before I even knew that RTS was a genre.... so officially Warcraft II was my first RTS :p and I voted for that.
To me warcraft and starcraft are about on equal grounds... though 3 races does help, I prefered the story and environement of WC.
Never played an age of empires game.
I'm not sure Total war counts as an RTS... it's part sim, part turned based ala Civ...
Heck all these games are great, it's a genre where there are too many good ones to chose a best.
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