Ooh, I have a cool solution for the stacking.

Have each diety get stronger for each player on it, but the power needs to be split amont the people under it. Have the player have to sacrifice something to the diety in order to gain "favor" in that diety. The more favor you have in a diety, the more percentage of the power you gain in that diety.

There are two ways that this can happen:
1. where all the favor is added together and from that, people get a percentage of the diety's power from how much of the favor they have. The diety would be super powerful by nature.

or

2. The one with the highest favor would have full benifits from the diety, and his favor would be considered 100%. People under him would have to divide their favor over his, and get a percent of their own. Like if the highest person had 1000 favor points, and another person had 500 favor points, the other person would recieve 50% of the benefit from the diety. The diety would gain only a small amount of power for each member and wouldn't be extremely powerful from the start.

The second one would be interesting.

For a game where stacking was implemented, you'd have to be clear about why stacking was so important. Like if you were trying to tip the scales in a war, you might simply see a natural reflection in the world of the stacking thanks to the forces being larger on the winning side - it would become like a measuring stick - versus if you were trying to become a god yourself, the pyramid idea would probably work a lot better.