Gameable History: Domestic Polytheism

I'm listening to The Ancient City. Part 1 describes indo-greco-roman ancestor worship. It's a kind of domestic polytheism which I don't think I've seen represented in fantasy fiction (except, kind of, Mulan). 

To summarize the gameable bits:

• Each family has a god, and their shared god is the defining characteristic of a family.
• If funerary rites are observed, then you join with your god after death.
• If the god is kept satisfied (by feeding the sacred hearth, watering the family tomb with libations, and singing your family's hymns), then they offer protective blessings.
• The primary blessing is warding the land, but the family god can also provide a familiar spirit to protect family members on long journeys, help find good spouses, etc.
• If the god is neglected, their strength will diminish, and your ancestors will suffer and fragment into hungry wandering spirits.
• Gods cannot split or merge, and you can only worship one god.
• You can however switch to a different god via emancipation/adoption, or via marriage (which is a ritualistic form of emancipation from one family and adoption into another).
• The god legally owns the family land. It therefore can't be split or sold to a non-family-member. Primogeniture inheritance is less about land ownership and more about passing on a sacred priesthood.