I was thinking to some original custom maps, that change everything from buildings to units in order to fit a certain theme. Several of these can make the object of an expansion pack....
Here's the first I was thinking of:
EGYPTIAN WARS
Light: Horus forces (eagle headed god)
vs.
Dark: Anubis forces (dog headed god)
Setup
The map is located in the desert - a clear area (maybe oasis?) surounded by huge sand dunes in the distance. Should have a very authentic Egypt feeling
Buildings
All towers are replaced with Obelisks
Citadels are replaced with Pyramids
Units
Horus Wariors, Archers and Priests (Eagle Headed guys)
Catapults = Griffin (lion body, eagle wings)
Giants = Sphinxes (huge human body, lion head)
Anubis Warriors, Archers and Priests (Dog headed guys)
Cata = Fire Scorpion
Giants = Scorpion King (mummy anyone?)
That's it for now, I'll improve this over time, add more examples and setups, but let me know what u think