Civ6 = (Civ5+Civ4+Civ3+Civ2+Civ1) x (the best aspects of all of these).
ok, that was easy.
Seriously, I remember posting several months ago, about units that were absent, that needed to be added, and I summed up what several people said.
Search in the Civ5, Civ4, Civ3 sections, and combine the best elements.
IMHO, Civ5 is too different from its predecessors to be called a true Civ sequel. It is more of a Steam version of Colonization, or the Playstation version of Civ, then, an improvement to the series beyond Civ4.
If I find the link, I wil add it. I know starting the year earlier than 4000BC (like 20,000) and adding snipers, more early units (pre-bronze), Guard Towers and something after modern age. As the term "Modern" usually implies the current age, the, age of time from roughly after WW2 to roughly the year 2000?
Perhaps, that time frame could be renamed "Modernization Era", with the current era, well, be named just that, "Current Era". Then, "Future Era" would still follow it, the way it always has.
This "Current Era" would add technologies and units that are the new units of today, such as the LASER systems that are built into certain planes, Hummers, and Ground based facilities.
The Mass Driver that was tested in the past couple of weeks, that could be used on land or via a Naval ship, is another example of technology that exists in it's early stages, that could be a new unit of a "Current Era".
Overall, Civ4 has the best features. It does need much more dialoge options during communications.
It is annoying when another empire gets attacked, asks you for help, but, then declines to offer it's new macemen tech to you to be able to defeat it's enemy.
I had to wait until the "Big Bad Guy" took most of his cities, so, I would then, be powerful enough to be able to demand the tech from him. I consider that a lame game mechanic flaw.
By the time I got it and built 1 maceman, his civilization was destroyed.
Gilgamesh has to be one of the most aggressive "Protective" leaders that I've seen.
Once, he takes Monty's or Genghis's religon, the two of them become a diplomatic pain to deal with, which usually ends in war.
Add a Growth Rate Slider Bar. This will comsume food faster. Wonders increase pop growth. Certain buildings and techs would too (Agriculture, Granary, Grocer).
Yes. Granaries store food. Storehouses store Olive oil, metal, marble and other resourses.
As I accrue more trade routes like 6-10 per city, I should be able to bring in resourses from many lands (think Ancient Rome). Those resourses would fill up my Granaries and Storehouses. If my Growth Rate is too low, I could max out my capacity, and the rest would goto waste, unless I sold it off to other empires, or increased my Growth rate.
Slavery is not done right.
When empires conquer, they bring slaves back with them to use or sell. Our population would go up, and the empire's food needs would increase right along with it.
Add Happiness resourses to water tiles. The phoenicians got their dye from sea animals. Pearls could be another.
Uranium should create unhealthiness like flood plains.
Change Financial trait to eliminate the +1 gold/t, and add Trade route gold increased by 25%. Double speed production of markets.
When a city is placed, and a resourse is discovered on that same tile (such as Iron or Uranium), we should be given the option to evacuate the city (basically, move it to an ajacent tile) so that the resourse could be properly mined.
Random Events added: An increase in Shark attacks have delayed fishermen on 1 tile for 1 turn. (result: loss of that tile's output for 1 turn)
An increase in piranha attacks have delayed farmers on 1 tile for 1 turn (same as above except must be a river tile)
Diplomacy
When an empire wants me to help them, they should be more likely to exchange techs to help me be better prepared to fight those foes attacking them.
We should be able to demand a tech as a condition of a cease-fire, Not be forced to try afterwards and be turned down.
Add Israel. The rest of the religons have their founding country in Civ4, but, not Israel?
Add Emperor Trajan of the Romans (EXP/IND).
http://en.wikipedia.org/wiki/Trajan