First off I've bought and played a lot of early access games and have been disappointed with more of them than I've enjoyed. Not the case with this game you've created a unique game that's really enjoyable. I'm looking forward to seeing what you clean and polish. I know this is early access and I'm sure many things are going to change and rebalance but I've played full release games that weren't as good. So haveing said that here's my thoughts added to the mix, I hope something in this ramble is helpful.
The great stuff:
1. I love the campaign mode that allows you to grow and specialize over multiple missions, great idea and I hope you expand on it and make it cover more missions. I'd love to see it stretch over 20-30 missions with some story, maybe even some single player (no ai) where you're racing against the clock to produce enough resource to avert a disaster or something.
2. The supply and demand mechanics you got in feel right, I actually feel like I have some control over the price of goods and that I can react to shortages.
3. Another thing I really enjoyed once I figured it out was that in campaign mode you can lose if the colony shrinks too much because of overly high prices of food or water. I think that a feature that should be added to multiplayer skirmishes. Something where everyone loses if they are fighting each other so much that they don't supply the colony properly. Although I'd say that that really needs to be documented better.
Polish I hope you add:
Tooltips and an encyclopedia - there is a lot going on in this game and not all of the information is readily apparent, more hover over information and a resource to go to in game to learn about the mechanics would really help. I watched you're let's plays and tutorials and that helped alot, if I hadn't watched those I'm not sure that even the tutorials would have been enough to teach me how to play
A list of hot key's and key bindings - From watching you're youtube videos it's obvious that you know all of the hotkeys, however I haven't seen any of them in in mousing over and I've seen you auto sell everything with a hot key, and for the life of me I can't figure out what that hot key is. I figured out spacebar pauses the game just because that a normal game convention, but I'd love to see a rebind-able list of the other hotkeys.
Sounds - love the music and most of the rest of the sounds but... are the voiceovers what you expect to have at release or just placeholders? I hope they are just placeholders as I find them to be kind of jarring.
Some UI function to cycle through buildings I already own. Many times I want to go build another mine next to one that I already have built and I end up having to scroll all around the map looking for the silly thing, if that function is already in then some documentation on how to find it or add in instructions on how to use that feature in the tutorial.
Documentation that going last gives you an extra claim spot - that's huge!
A tooltip on what your stock price is headed to as you go into debt or pay down debt, it's really unclear to me just how my debt affects my stock price. Yes the tooltip shows the x3 or x4 penalty for your debt. But in one game I ran up my debt to about 80k and then paid it all off very quickly and I couldn't really determine that it had a huge impact on my stock price.
Game balance or mechanics I'd like to see:
Debt doesn't hurt enough or the AI doesn't use it enough - I've seen this mentioned in alot of other post with a lot of other recommendations on how to resolve it. Personally when I turned on the stricter debt option in the quick start game it was a lot more fun for me. But here are possible solutions that I thought of to makeing debt feel right:
1. have the interest rate on debt work on a supply and demand just like every other resource in the game (basically like a simplified bond market) if other people are in debt then you can buy that debt and be paid their interest, and the more debt they have as a ratio to their stock price the higher the interest rate they have to pay.
2. Instead of haveing the interest on the debt add to the balance of the debt instead have the interest on your debt subtract from your cash balance. Basically you have to make an interest only debt service payment (which is pretty realistic in the real world on revolving debt) if there isn't a large enough cash balance to amke the debt service payment then have the interest rate increase (1%-5% for each defaulted payment)
3. Some way of limiting buying out someone else's stock while your deeply in debt
4. a softcap maximum amount of debt you can have based on a multiple of your stock price. Again this is a common thing for real companies that their bond prices are based off of a debt to book rate value, and when you exceed that soft cap no more expenditures are allowed until you pay down under that cap. This would solve the buying out opponents while your deeply in debt.
When shipping offworld the ability to auto buy and ship even if the reserves aren't in your stocks. It doesn't make since to require the extra mouse clicks to have to buy the resource first then click to ship it.
Science faction just feels too weak, the tutorial was by far the hardest and I've tried to play both skirmish maps and the campaign as science and they are way harder to play than any of the other races. The only thing I can think of (and this might be overpowered) is if you put a steel mill on an iron mine it generates the steal like normal and half of the amount of iron a normal iron mine would.
I said it before but I'm going to mention it again having a non player colony that drives supply and demand just like whats in the campaign mode so that demand for life support goods goes up over time (and maybe having the income from pleasure domes go up as well)
Lastly it feals like there needs to be more uses for carbon and aluminum. After the initial build up phase the prices seem to tank with not much to do with them.
And I know there are a few other thoughts but now I want to go play another game 
