So many great games mentioned, like Sins of a Solar Empire (will have to get back into it sometime), Homeworld, Freespace, and Galactic Civilizations. Thanks for reminding me of them!
Oh, and since we’re on the topic, here’s a great playthrough by Tom Francis that showcases how great the Galactic Civilizations II AI is.
Although, I have to ask: no Endless Space? Not even 2? I had a great time playing it, to be honest. Probably not as complex as the aforementioned GalCiv but it was a ton of fun for me, nonetheless.