Level one players do …something…to anger a demigod (Say, Orcus.) and he’s coming for them. They have a year before he can get to them. But he’s on his way.
Maybe they kill a very low-level acolyte, but this guy had inherited over the generations an ironclad boon from Orcus. And as he dies he tells the players Orcus is coming for them. It’s up to them whether they believe it. Its more fun if they don’t cause you can shape various encounters around the fact this demi-god has abandoned his realm and is working his way to them. Orcus followers become zombies rather then die…stories get shared of great battles on other planes, that sort of thing.
The point is this threat is always in the background as time ticks away. How do they respond?
That’s a pretty standard plot arc, especially in the horror genre. It’s a good way of giving structure to a campaign but of course your players have to engage with it (or their characters have to be forced into conflicts with the god and his cultists), and it can turn into just kind of a “Chase of the Week”
situation where the players are constantly trying to escape unless you specifically provide ways for them to build up their abilities to prepare for a confrontation. It’s probably best for a limited duration campaign of 8-12 sessions because it will eventually become repetitive, and once they have (presumably) defeated their archnemesis the story arc is essentially over. (See MCU Phase 4 for why this is a narrative problem.)
It’s a good idea but it really has to be well-paced to work, and the players have to be willing to go along. I would be more inclined to make the killing of the acolyte and the vengeance of the god a kind of throwaway plot element where you get a hint about some ambiguous emerging threat every few sessions and feed the players clues that it is actually tied to their incidental killing of this minor NPC way back near the beginning of the campaign, and let them suss it out from there; even better if family members or subordinates of the dead acolyte show up once in a while presaging supernatural vengeance, or promising to help but then betraying (or being betrayed). But then, I tend to favor sandbox campaigns where the players have freedom to explore and find their own trouble, and as the GM your scenario prep is just laying out a few locations and elements for them to interact with and see how the story develops rather than trying to railroad the party to a defined goal.
Stranger
How many have to survive for the quest to be successful?
And I am definitely not asking as a Chaotic Neutral thief who would never ever betray their beloved team-mates for personal gain.
The only impetus from the players is get them to kill a low level cultist. Shouldn’t be too hard. After that they can just have their low level adventures at will. But a clock is ticking….which they may not even be aware of
But all kinds of stuff can happen like people trying to kill them to stop Orcus or using them to kill Orcus.
Or maybe someone wants to wreak havoc somewhere so they transport the party there.