This game continues where the other game Age of Empires II left off. Which is the Imperial Age. Age III goes from the Imperial Age to the Colonial Age. This means new technology. For instance Musketeers, better Cannons such as Mortars, etc. This games Graphics are one of a kind i have not seen any rts with better graphics. If you want screen shots i can add some later.
The game takes place in Europe, South America, Central America, North America, thats all i know so far.
There will be ocean battles like pirates and stuff like that. This time trains will be incorperated in the game. Which i would like to see what they use them for. And how that works.

These are all of the things I know so far.
If you have any Questions ask away i will try to find an answer. If i can't find it yet that means alot of the answers are either not out yet or they are just rumors. CLick here to goto the article and to view 22 screenshots

This game looks incredible... blows all the other RTS games out of the water. Here is the main site, has some pretty sweet screens:

http://www.ensemblestudios.com/

yes the detail in this game are way to great. The snow actually has alot of texture in it too.