D&D - Involving the Gods; Boons and Banes
I'm in the planning stages of a custom setting for a new campaign I'm aiming to start next year with my current table. We're doing PF2's Kingmaker and AD&D's Temple of Elemental Evil in the meantime.
The game is to be Viking themed, in that the starting locale and civilization will be structured in similar ways to the coastal Scandinavian settlements and there will be an on/off season. During the on season, they will board boats and sail many hundreds of miles across water to distant lands to find dungeons and ruins to loot, with a clock they have to keep an eye on; the expedition can only afford to be out for so long, and they need to ultimately make a profit. During the off season, they will be home and can spend time locally engaging in low-tier politics, explore the untamed parts of the continent, or both.
I'm intending for gods to play a more concrete and available part in this game and have been chewing on how best to represent that mechanically. I discovered that one of D&D 5e's supplements for a Magic: The Gathering setting, Mythic Odysseys of Theros, does something similar and has mechanics for tracking Piety with a given deity, which comes with boons at specific breakpoints. I liked the idea, though I'd be making my own boons for my pantheon rather than use these as-is, especially since I wouldn't be running this game in 5e, but rather in AD&D 1e.
I have a group chat with a few of my players that I can trust for this kind of thing to bounce ideas off of for various things, so I put this forth to them and got their thoughts. They universally thought the example boons from 5e were too personal and individual for the kind of stuff Norse gods would get up to, and there wasn't really a way to track a given deity's disdain of you in a similar manner. They also didn't like that you could track the Piety with a discrete score and could reliably measure when your next boon would be.
What we settled on doing is utilizing my custom tarot effects we're already doing in my regular AD&D campaign, but having it apply in certain regions or during certain stretches of adventure. This would allow for randomly coming across an avatar of a god and earning a minor boon or bane for assisting or denying them.
One option here is to not let them but still use the mechanic. Keep it behind the screen.
The fun part of an active pantheon is the fact that they can't be tri-omni gods (all powerful, all knowing, all good/evil). It basically makes them a bunch of kids sharing an ant farm. They can see everything at a surface level, but it's very big picture and they need to lean in with a lense to give individual attention. They can interface with the world directly but that direct action will be clumsy and violent so they need specialized tools or for their folloers to lay the groundwork. They can see and understand major threats, but breaking the glass to deal with it is a last resort and they will need focused interventions.
So a big factor in creating a god and their systems come down to how the divine ecosystem has evolved and why is any of the events happening. The big question being, why do the gods really care. They are not all-powerful, so the how do mortals give them power. They could be symbiotic with their believers so having their ideals recognized is literal nourishment for them. A transaction that is repayed by reserving and maintaining a heavenly plain for the souls of their following.
Or since it is Norse based, each god wants to fill their halls with the souls of only the best warriors. It's a sort of insurance policy that prevents petty disputes amongst themselves from going too far. But falling too far behind could lead to a hall being absorbed so there are complex politics and alliances that keep the peace.
Or talking to your gameplay loop, there are resourses and places of power scattered across the world and capturing them give gods the power to influence major aspects of the world according to their motiefs. And the off-season recalibrates the world according to all the changes in the last round of expeditions. Gods that have a lot of resources have a larger macro influence but their power and attention is spread thin. Gods that hold less will not have much influence on a grand scale but can focus their powers more meaningfully.
As for player systems, I personally wouldn't use systems of piety when dealing with gods that are being direct and overt in their actions. At that point religion isn't about faith. It's purely a practical matter. If your players feel a personal relationship with a god is not exactly in the spirit of the setting, maybe a more transactional relationship would be in order. I can imagine something along the lines of the game Hades. As you go on a run, you have opportunities to accept a wide variety of boons. And you have the choice of specializing in one god or finding synergy across multiple.
With more general boons that could reset or expire over seasons, you can have the players experience your entire pantheon without sacrificing their character level. I can also see it playing into the setting. Warrior faiths for a warrior culture. Temples include training grounds and armories specializing in different schools of combat. Heretical sects that exist in between. And players show devotion by how they choose to go into battle.