If you asked me to give an example of a very simple thing to add to the game that would improve it leaps and bounds, I'd have to say better tooltips. Right now, the game is very basic, and I understand that not all the mechanics are in place yet, but in its current state, GC3 has very poor conveyance. Say there's a plot of land with a symbol on it. It says it improves X and Y in the tooltip. What's the difference between the upward green arrow and the yellow carets pointing in 4 directions? Is one a bonus to something built ON the square, and the other a bonus to things built AROUND the square? Are they both bonuses to things built on the square? What's the difference between Tourism and Influence? Is there a connection? What improvements do I build to improve the former? Etc, etc.
Now, Asteroids are back. In GC2, you could mine Asteroids for a production boost. Great mechanic, ensured you could build things on a planet without needing to put factories on it. Can you still do that in GC3? How? If not, what do Asteroids do other than block movement?
I should not have to ask on a forum or alt-tab to a wiki to figure those out. Naturally, there are going to be mechanics that require more than just a tooltip to explain, and for that, there's something we all know and love, the Civilopedia. Anything long-winded, awesome, and complicated goes here. It's a place we can look to in game to figure out the difference between our ass and our elbow, and if the devs feel creative, some lore as well. It's a feature that GalCiv 2 sorely lacked, something that desperately needs to happen in GC3. A game of this scale needs an in game manual. The most important part of any game is being able to play it. The more we could learn about that in the game itself, the longer and more excited we'll be to play it. At its core, a Civilopedia isn't just a manual; it's a list of all the awesome things the game has in it that you don't have access to yet. It doesn't just tell you what the awesome things are and what they do, it tells you how to get them.
Still, a different space 4x called Endless Space got away without having a Civilopedia, and it pulled that off by having an extensive yet easy to read tech tree, excellent lore-filled tooltips, and detailed descriptions that didn't just tell you how to play, they gave you a glimpse into that game's ongoing story. If you can pull that off, more power to you.
One thing that bothers me about this game as it is, though, is that it has a lot of moving parts, and a lot of the time, you have to figure out what crank you're supposed to turn to make the fun come out all on your own. A nudge in the right direction would be much appreciated.