Ideas:
# horse field - mainly to get that screen full of horses...
 - ability to change horses? But horse you choose may disagree with you
 - apple / fruit to appease horse
 - high horse-whispering skill required?
 - horses all quiet and feeding when playing as Zerka / Bleda, but immediately stampede when playing as Attila / when Attila is coming
 
# a world that is alive in every aspect! 
 - wind in the trees and grass and hut roofs
 - birds and butterflies!
 - stray leaves!
 - clouds!
 
...but I still don't know what the core gameplay will be...

cantering http://www.youtube.com/watch?v=RTbqfIUeS4E&feature=related
all gaits, including backup! http://www.youtube.com/watch?v=t4zdTn02PWQ