ok then, new great people system
which GP is generated is no longer random, each type has its own counter like in civ5. no more getting the one that had 1% chance, ruining your strategy
( before I forget, this also reminds of another very welcome change: fights at odds close to 100% are now rounded to 100% . no more spearman beats tank!
)
GP also have many new abilities, like discovering new resources, allowing new equipment etc.
GP points are modified by two additional values: city population ( big cities mean more GP points ) and city culture.
culture is way more useful, as it now gives tangible benefits instead of simply growing borders ( borders grow slower now though ) : some buildings and civics give bonuses based on the culture level on the city, and culture can be used to generate more GP and build more improvements.
each population point also gives +1 gold, but city maintenance is much higher to discourage city spamming.
the "military unit cost" is gone now, so for example you don't pay a crapload of gold as soon as your units step outside your borders. feel free to explore the wilderness, but be vary afraid
units still cost regular maintenance costs though, and there's a new mechanic "City garrison" : each city can have 4 units garrisoned in it. garrisoned units don't count for the "max number of units" cap and pay half maintenance costs. garrisoned units become immobile though ( you CAN remobilize them but it costs some 200 gold ) , so only use it to give each city a reasonable defense without eating your military supply
next, I'll have to explain something about spellresearch, the new promotion system and the new wilderness mechanic...