I think you mean Galactic Civilizations 2, since I'm pretty sure 3 doesn't have any mods yet, not being released and all.

I have StarDrive, but havent played it that much, since i prefer Rebellion. It does not mean its bad, though, actually there are certain aspects, which are pretty cool, and i wish they were transferable to game like Sins...

Aside StarDrive the only 4X space games i ever played are Ascendancy and Pax Imperia 2, so its kinda hard to compare for me. I think both of those games were basically real-time, while you could make time run faster/slower or pause it completely, and StarDrive is the same way, so there is no "turn" button. Even though the game says various things take X turns to complete.

One thing i liked about the game, even though this was kinda difficult to comprehend at first, is the how resource system works in this game. I mean, certain planets are good for food production, other for production, you gotta import/export these goods and people between planets to supplement them with stuff they need....this was completely new to me - and once i kinda understood, how it works, and got it going, it felt really good.

Oh, and there is one stand-out thing i guess, the ship-designer. Again cant compare to other games, but here its really well done i guess, gives the game that sand-boxey feeling, where you can speculate and play-around with various designs...obviously there are some rules to adhere to, so you need actually think, what are you doing, for example all the fancy weapons and shields need to be powered by strong enough power generators, you actually to connect them via power conduits, etc... if you like this kind of stuff, its definitely a game for you.

The negatives for me its the pure single-player nature of the game, i like to play my games with my friends. Additionally one thing i particularly dont like are the races. Not only they look like various animals (owls, samurai bears, wulfen, etc), which kinda makes it bit less serious, and i dont like that, but most importantly, they are all the same basically. You make them unique by choosing few special trait at the beginning of the game, like "industrious". "meticulous". "astronomers" or "polluted homeworld". otherwise their research trees are pretty much the same. And thats never good enough for me  when compared with pre-designed races like those in Sins. I way, way prefer the Sins approach.

Anyway, I guess it depends on your preference. The StarDrive is probably less complex and more stream-lined game than DW, at least it definitely looks so when seeing the DW videos on youtube. Personally i need certain things to be schematised, abstracised. Dont want to deal with every single detail nor do i like to put too many things on auto, cause it feels like it is playing itself then. Thats why i chose SD over DW.

Starpoint Gemini 2

http://store.steampowered.com/app/236150/?snr=1_7_15__13

Early access and brilliant game.  A game that incorporates parts from other space games, as well as it's own features.  It's different.

I played it quite a bit since buying, and can tell you it's very addictive and a breath of fresh air from all of the x4 clones running around at the moment.

StarDrive is pretty solid. Its a touch buggy, but the dev is making a new version in unity. I bought it hoping it would be GalCiv III (quite some time before GCIII was announced), it was not, but I do not regret buying it. It gets economy right, for the most part, and the ship-building is unique, although I prefer the GalCiv II style personally. The AI is not the brightest though, especially the ship AI and the planet governors (eg. industrial governor still does tons of research). 

Overall, I would say to pick it up (I give it a 7.5/10), it on the steam holiday sale for 66% off right now. 

The only space strategy game that could make me play it more than once or twice is Endless Space. (too bad it seems I started playing space strategies later than everyone else and can not really enjoy older games than SoaSE)..

EDIT: My favourite game of all times is Sins of a Solar Empire just Endless space is the only OTHER space strategy game I could play for a longer time without getting bored or too confused.

It is a bit strange I am a warmonger in Sins of a Solar Empire, but in Endless space mainly due to battles being somewhat poor, I am an economist and researcher (though I do wage wars while improving my economy). Manageing research and improving the economy while being defensive here in this game feels much better than in Sins, and to finally achieve some kind of non-military Victory. 

Oh and it has many races, though racial diversity is not that huge, and some races are just bad.

Endless Space is a TBS, I got really tired of the horseracing of competitive Sins Multiplayer, and playing against the mass-suicide AI or playing with incompetent noobs (many times they can't even speak or want to speak english) is not a fun option for me anymore..

I Like that ES has more planet types than Sins had for many years.. And you can terraform, remove anomalies, and that this game really is in a galaxy, not an abnormal extrasolar system having 30 or more planets and stuff around a single star (I hate multi star systems in sins, bad to play on them).. I like Endless Space's system focus instead of managing each planet individually.

Oh, and I dislike many space strategy games because of their overly complicated resource management. I can't remember which game had 8 or more resources I couldn't even figure out my income of those and what to do with them.. Endless Space is not like this fortunately.

Tech trees are indeed a bit funny and sometimes not very logical, but after some time you will remember what each of the 4 branches do, and which branch to focus on if you want something new like a luxury resource or a new planet colonisation tech. Good thing there is a good in-game explanation for every tech there, and the icons are helpful as well

Distant Worlds is the only game that fits your criterion.

There are very few (a literal handful) real-time space empire builders and Distant Worlds is the only one that isn't a combat focused game (i.e. not an rts with delusions of grandeur).

I can give you a list of good games that don't meet your criterion.

For non-empire building space strategy exploration games there's Space Rangers... and after that you need to go really retro with Star Control, Escape Velocity and Starflight.*

For space economic empire building there's the X games (ignore the disaster of the latest game).

And then the (great) turn based space 4xs are:

Sword of the Stars (the first one). This has real time combat.

Space Empires IV

GalCiv (obviously)

Master of Orion

and after that it gets sketchy...

As you can see  we aren't exactly... blessed... with space strategy games of any kind let alone meeting your very specific requirements

* Maybe I'm wrong but I think these might be the kind of games you're really after?

It plays most like Paradox games (europa universalis, crusader kings etc).

@cayote re: Distant worlds game and turn based. I am with you. I strongly prefer turn based games. I play DW a lot, as a 'turn based-ish game. When i first scouted out Distant Worlds ("DW") I was put off by the RTS aspect of it. However, when I read a few posts here at SD, and then went to DW forums, I discovered that while DW is labeled a RTS game, and can be played as a RTS game, there are other viable (turn based) approaches enabled by DW's game interface. DW allows for an incredible number of choices regarding automation or manual control of almost every aspect of your empire. You may pause it at any time, and enter, change, etc. commands, policies, etc. DWs can be a micromanages dream come true, or you can turn on all the automation and ride the whale. Players choice. I play in a smaller galaxy, and turn off almost all automation. The tricky part is getting a handle on the missions you can assign to military fleets, the 'fleet posture,' and how they interact with "empire policies.' But its fun. There is a steep learning curve if you turn off automation, but well worth the ride. And i love designing my own ships from the ground (err stardock?) up. Further,there are multiple, well researched, guides on the DW forums, and you-tube videos. Just seek out the ones that fit your play style.

If you do decide to try it (I'm not sure if a demo is available?) I would be happy to guide you a bit to smooth out the initial learning curve, mostly by pointing you to the most appropriate 'guide.'

edit:  spelling. grammar.

I like Endless Space ok - it introduces some interesting concepts like system instead of planet focused management and tradable commodities - and I like the different planet types and anomalies.  I hope there're some interesting things worth considering for GC3.  But by and large ES feels flat and stinks for customization, whether ships, adversaries, tech, etc.  I'd rather be playing GC3!

wow, cardinaldirection, I had no idea someone actually did this. Sega rocks (diplomatically speaking). Does the UN know about the boards?  

Way cool! 

Way cool!!!