In the original GalCiv, you had I believe 10 effective overall difficulty settings based on how many AIs you picked and how much smarts you decided to give them. Generic difficulty settings, all around.
However, that's a little one-dimensional.. Wouldn't it be better to have more control over the difficulty settings? For example, having two separate controls of AI difficulty:
-Adjust Intelligence (Fairly obvious what this does; at lower levels the AI should "intentionally" make bad decisions, at higher levels...)
-Adjust Strengths/Handicaps (This would let you either have the AI play by the exact same rules as the player (And I do mean the EXACT, at least short of them knowing the layout of the map) or give the AI a boost. I definitely think an option, even if it's not the default "Normal" setting for purposes of scoring, should exist where you can play where the AI is given absolutely 0% extras that the player does not have. As I recall someone discovered that the AIs in GalCiv 1 almost, but not quite, played by the same rules. And then of course you could cripple the AI with staggering penalties. This would let you play against the super-genius AI that can practically do no wrong, except they have -100% to their abilities for example.
And then on the player's side:
-Adjust Intelligence.
-Adjust Strengths/Handicaps (Same as above.)
There could also be a grab bag of difficulty settings. I'll throw out a few.
-Head Start: The AI is forced to sit out the game for the first X turns. Alternatively, the player is forced to sit out the game, or if that's not feasible (Who wants to wait, etc. - I'm not sure how long it would take the AI to play through "X turns") just give the AI an artificial looking head start (They would start with the kinds of things you'd expect them to get X number of turns
into the game.)
-No "Rushing": Unless GC2 has changed considerably in the early game compared to GC1, and as such fighting isn't really.. existent, this wouldn't be meant for the early game. No, this would mean no fighting until particular eras of galactic development. Thus (Theoretically) resulting in large, untried but well developed fleets suddenly being let loose.
Some obvious ones:
-Random Events: Ability to turn on or off, ability to control strength of severity, likelihood of a certain level of severity & frequency (In other words, make it common for someone to find a Ranger but rare to find a working Terror Star or whatever), and either positive or negative (Space sharks spawn every few turns but you never have to worry about the Dread Lords.. or whatever.)
-Minor Races: Turn on or off. Set degrees (One planet nobody Vs. Six system juggernaut), set frequency (One planet nobodies pop up everywhere, Six system juggernauts once or twice per game.) And all of the other controls for the regular AIs (Smarts, handicaps.) Additionally you could set a range of randomness to their intelligence and abilities rather having every minor that spawns be dumb as dirt with -200% to abilities. That way some minors could be vast corrupt empires, or a lone star genius.
Finally.. how about a Sandbox mode of some sort?