I think a new civ around keeping your units alive so they can get honor, or something that buffs your units, and it decrease or increases depending on what happens in the map, or what that unit does.
example: spear man with 10 damage kill archer it progress on to another level, and now does 12 damage, or enemy builds wonder spear man with 10 damage decrease down to 8.
I think this would be a cool civ to play. (I was thinking maybe it could be Japan, or something like that.)
note: each type of unit probably need more honor, or something
example with a mangonel I need 3 kills to progress up the mangonel.