Or maybe a later version of 3?
I really like this game - my favorite 4x game so far! (Well, okay, Alpha Centauri might tie, but that's tough to get running now.) However, as much as I like it, there are some things I wish it did that I don't know if they could be modded in.
* Race specific ideologies. How does each race order their values and culture to be "good" or "evil"? For example, the Krynn could have their internal war of religion vs. crime syndicate. The benevolent options give morale bonuses and influence as they spread their faith; the malevolent options give money and espionage. The Drengin are all about the superiority of their race. Would "good" Drengin step in as paternalistic masters, conquering others as unruly children? "Evil" Drengin might follow the Korath philosophy of mass extermination. What would an "evil" Altarian look like? A "neutral" Iconian? A "good" Yor?
* Blind Tech options. Alpha Centauri used to have an option where you could pick a priority and your discoveries would focus in that area... but you didn't know what you'd get. For example, if you chose military research you might wind up with a new weapon, or some new armor, or a defensive improvement. If you chose industry you might get a factory upgrade, or new worker specialists. Be nice to see that in GalCiv.
* Trade Route disruption. If I'm at war, I'd like to station ships along a trade route and do some privateering. Maybe a command option that nets you a small percentage of the value of the route.
* Intra/Intercivilization civilian travel. Instead of penalties to production, make citizens move from low approval planets to higher approval ones. Yes, I can ferry a group on my own but why wouldn't they do it themselves? Balance the increase in expected happiness against the distance they have to go, and possibly living in another civ. Would they travel 10 weeks to get a 2% increase in happiness in another civ? Probably not. Would they travel 2 weeks to get a 50% increase on another planet of yours? Definitely.
*Some kind of galactopedia that I can look information up in game! Especially on stuff that isn't clear from descriptions.
*PBEM/Hotseat play.