This game would be absolutely awesome if it wasn't.
First game I play on Default settings. 700 planets, normal aggressiveness, 19 alien races all with starter empires like mine. Took about two hours to win through expansion (AI didn't even begin to match manual colonization rates).
Went online looking to see where the difficulty sliders were. Found that setting aggressiveness to "Chaos" and enemy starter empire size to "Thriving" or something (middle setting) was supposed to up the challenge. It didn't, even remotely, but it did make the game take almost 5 hours.
Here's how I went about it. 700 planet galaxy. Enemy started with something like 10 planets apiece and a dozen free techs or so. 19 of them again. Handled all expenditures (colonizing, ship building) manually, built a few scouts and three colonizers right off. Expanded, colonized, killed a few pirates. Eventually make contact with a few alien empires. Problem 1: diplomacy.
This is something you'd see a lot of in Civilization and GalCiv - tech trading. Once you get a tech that another empire doesn't have, you trade it for one of theirs and maybe some cash. Then you go to the next empire. Then the next. They don't (properly) trade with each other, so you're the sole tech broker in the galaxy. Within an hour I had all but a couple of super techs greedy races were holding out on, with plenty of spares to sell to the weaker races. I got the currency to buy the first tech from Problem 2: colonizing.
One of the colonies I happened to snag was in the same system as an enemy colony. They started to get mad at me, so I decided to sell it to them. Whoops - a planet I'd just blown 6,000 creds on to colonize was worth 1.3 million creds to them. Not only did I avoid a conflict; I got several techs and creds for more colonizers. I expanded in every direction as any proper 4xer would, and since I was new, I did so without regard to luxuries, planet viability, or any other nonsense that sensible AIs were probably paying attention to - I had all the creds I could ever spend from tech trading. I spread like a plague, built a ginormous fleet or troop carriers and capital ships, and once I had triple my closest competitor's total firepower, declared some wars (which was pretty easy, as everyone loved me up to that point). At this point, I ran into Problem 3: brain dead AI.
As things progressed, I let the AI handle more and more of the burden for me, until it reached the point that I let it run itself on 4x speed and just clicked through annoying treaty popups and tech traded a little to support my million cred a year deficit to support my fleet (how an enemy comes up with over a million creds a year to blow on my crappy trader techs I've no idea, but enemies with as few as 5 planets were doing it - maybe they were playing the game "properly"). Something that became immediately apparent was that not only did the enemy AIs (who started to all really hate me after I set everything to automatic, since Robot Me is an ass) refuse to attack even a single one of my planets to conquer it; my AI fleet was doing the same (that is to say, killing some ships, but not loading or assaulting with troops. Took over 2 planets in the course of an hour with 5 - 7 wars running at any one time and most the all enemy fleets and starbases dead [I helped a bit with the starbase part]).
After an hour of that crap, I paused the game, took manual control of the fleets, formed a few megafleets in planets with several starbases, and took over enemy empires manually, one system at a time. Fun part is that after the near hour spent organizing the fleets, they stomped enemies to paste with superior numbers and superior (traded) tech in no time whatsoever as I leap-frogged attacking fleets, allowing every other fleet to refuel while the fresh ones assaulted. With top tier engines, it took about a minute to take an individual system with an individual fleet (although I had to be careful to only invade enemy planets with one troop transport at a time, or I'd get to wait half an hour while the things tried to cram into a planet to get more troops, which's really rather annoying). I only had to kill three empires (two smalls and most of a large) to meet the 33% to win default requirement, which I didn't mess with since it would make games take longer, but not make them any more challenging.
Now I don't mind that the game's single player. I like multiplayer for competitiveness, and the game certainly has enough minutia to get competitive, but I can always play an RTS like Spring for a quick fix there, or hunt down an old Stars! game for one turn a day year long games. I love the amount of detail in the game and the way it all meshes, but I didn't have to use a bit of it to win. I used default ship types the whole time and had a super easy time - didn't even bother to put guns on my civvy fleets. Who needs money when you're trading for millions at a shot?
I know there are all kinds of requests for improvements, and I'm sure they'd all make for a better game (scroll smoothing would be absolutely ducky), but unless the following three items addressed above are corrected (and I don't think they'd be too hard, though I didn't code the thing), all of the charming random bits and detailed minutia won't mean a thing since you don't need an edge to beat an AI that doesn't fight back, or a healthy economy to earn money when the enemies will just give you theirs.
1) Cause the enemy to either trade with each other, or not trade with the player. This is a basic lesson from Civilization. End one-sided tech trading (or monopolized tech brokering, if you prefer).
2) Increase the rate of AI expansion, or penalize players more for colonizing dead worlds. As far as I know, eliminating monopolized tech brokering would fix this by itself. Also, give the AI a realistic way of valuing planets in a contested system. Certainly, a good planet might be worth 1.3 million creds to an enemy player, but why pay that much when ~4,000 for a troop transport and ~8,000 in destroyers could get it for you just as easily (especially when the player selling the planet has a dozen fewer techs than you do and a starter empire).
3) Make the AI take planets. This is by far the most important point, concerning both enemy AI fleets and your own when AI controlled, as tech trading can be seen as an easy to win mini-game. In my mad dash for expansion, I had planets spread all over a 700 planets spiral galaxy. Any local enemy that wanted to could seize my far-flung planets and there was little I could do to stop them as even max-tech fleets don't instant warp. During the course of my longer game, I lost around 30 planets to the AI, most in contested systems. Every single one of these I lost to defection. As far as I know, the enemy AI players never even built Troop Transports. If they did, they were even more useless than mine (my 45 transports captured 2 whole undefended planets in an hour!).
I really like the atmosphere of the game, and I love minutia - especially AI players that will surprise you once in awhile (although I can't think of any game where they come even close to thinking like players - efficieny, many are good at, but how many are willing to risk 80% of their fleet in single blitzkrieg to overwhelm enemy home systems, trusting shock and surprise to protect their own planets since all of the ships are away?). I don't think the game's good for a few more plays, even if I max the size of the enemy empires on max aggression, if they won't ever, EVER attack in earnest, or even raid significantly. This game could be the best thing out there right now for scope and scale. At present, it isn't even a match for GalCiv 2 (where the enemy could and would overwhelm and kill you if you were unlucky or careless enough), let alone Moo2 (where the enemy could and would overwhelm you if you weren't careful and lucky).
Anyway, nice effort. FiX pl0x.