PRODUCTION MUST DIE!
So much newb confusion, bad economic management and bad AI comes from the existence of the production mechanic for social and military development. it is a totally superfluous level of complication. everyone ultimately (often painfully) finds out that the production slider must be at 100% for an efficient economy. this effectively makes maintenance and construction costs the same thing. the balance between building manufacturing generators and buildings that apply % modifiers is effectively a production time vs. production cost decision, as bonus construction is cheaper.
if that's the only decision you're making when designing worlds, then wouldn't it be simpler just to be direct about it? ditch paying for production in a round about way and just make us pay for the buildings or ships themselves as we want them. the buildings on the ground will either reduce construction time or construction costs. EASY. there is therefore almost no way for a player to get the economy wrong. skill is all well and good, but the current economy does not give you any room to succeed, only for new players or bad AI to muck it up unnecessarrily. the only interesting approaches it leaves open are the ridiculous ones, like the all-factory strategy.
the only production that should be kept is research production. your totally installed capacity determines what you can spend and how much you get for it: you then drag the slider as far up as you wish to allow.
TACKED ON FEATURES SHOULD BE INCORPORATED INTO GAME MECHANICS
I'm talking about you ethics system. Ethical alignment should be determined based on real ingame decisions like the use of inhumane invasion tactics, massacring planetary populations, starting war without provocations or declarations, not by arbitrary screens with bad art design.
political change should be properly encorporated: if you choose to allow elections then they should be totally independent of you, rather than you choosing a party that succeeds based on approval. elections shouldn't limit the player, only encourage certain approaches: ie, if the pacifists get in, the cost of warmaking might increase, but diplomatic abilities would be improved, encouraging a peacefull solution.
the UP should respond to galactic developments, make peace treaties and empose sanctions, not just generate a random event every month.
minor races should not be arbitrarily different. if a civ is less expansionist or fundamentally born to loose, then model this with AI and racial abilities, rather than arbitrarily saying they can't colonise.
SPACE SHOULD BE INTERESTING AGAIN
when you think of all the possibilities that have been discussed in sci fi and real science, the way that planets are boiled down to just one number and a tacked on environments system is just sad. the game needs to get away from huge lists of effectively identical planets with different capacities, and back down to unique, interesting places that the player actually cares about. this can be done in a way that is just as user friendly as the current system. i'd give each planet both a capacity rating and a habitability rating. the first determines how much you can build, the second effects morale and determines the rate of population growth and the point at which population stops increasing (along with farms, taxation and other factors, see the total war games for a great example of how this is done). habitability is determined by the planet, racial factors and technology, capacity is inherent. factors like gravity, atmosphere, tectonic activity, temperature, and orbit, all of which can vary independently, making every world a unique place to explore. each factor has a corresponding tech tree branch to improve habitability. every planet should be colonisable, even if it is just a tiny outpost. when a world is unlikely to be self sustaining with current technology, the player is warned before colonising it. very few worlds should be as habitable as your home world: you evolved there afterall! this makes civ power much less proportional to empire size, helping smaller civs and slowing the steamroller effect.
THE CARTOON ART STYLE AND ATTITUDE HAS TO GO
there are absolutely no screens for GC2 i want to show my friends. plenty of other strategy games like SOASO get this better. a way must be found to keep ship design whislt keeping the ships looking sensible. i feel like i'm playing a board game rather than defending an empire. GC has no atmosphere. lots of the flavour text destroys the fourth wall. how am i supposed to care about the game world when i'm talking to a race of aliens that look likesquirrels? this attitude may be acceptable for an indie game, but not if you want to be taken seriously as a developer.
there is loads more i can say but i'll leave it there for now. despite it all, GC2 is a great game and i know GC3 will be better.