The 12 civs would have 12 gods each- 3 major and 9 minor. They would be separated in expansion packs, with 1 or even 2 years development between them. The base game would have Greek, Egyptian, Norse and Roman (which would replace Atlantis, though of course it won't be exactly the same thing); the first expansion pack would have Mesopotamian, Yoruba, Celtic and Slavic; while the second and last one would have Aztec, Chinese, Japanese and Hindu.

That I agree with, had to realize some people want a Medieval civ with Arthurian deities (?!) and even a Lovecraftian civ which breaks the game's immersion of ancient civillizations. However 12 is a PERFECT number for playable civs and the major god selection only changes the gameplay (researchable technologies, god powers, wonder design and myth unit selection) or an occasional extra building such as Ouranos' portal towers. Visually speaking, the 3 factions of each civ are almsot the same. Don't you want to sacrifice people to Huitzilopochtli while commanding jaguar warriors, build ziggurats to honor Marduk while summoning Pazuzu in Babylon, watch druids and Irishmen battle for the Morrigan and erect Stonehenge, samurais and ninjas praying at Amaterasu's temple, control war elephants and a powerful empire worshipping Vishnu or visit the African savannahs under the tutelage of the Orisha deities?