Campaign outline

Prologue: Arrival at the great river

After some dangerous event, the player characters are snatched from their home worlds/planes. They wake up in a seemingly endless dark hallway that eventually brings them to a bright portal that leads to the desert. So far, they don't know about the long night, so they should probably look for shelter before sunrise.

Yes, this is pretty much the classic isekai trope you see in manga and anime. While it might be a bit overdone but I want the characters to be just as new to this world as the players are so I'm sticking with it for now.

Act 1: Enslaved

After a long march through the desert and some small challenges, the player characters arrive at the building site of Shuramud's new temple. At the edge of the workers' camp, the will be apprehended by two sun elementals. Without any explanations they are stripped of their weapons and get assigned to a tent. They have a few hours to get to know the other workers before their first shift starts.

For now, they should get the impression that they died and are now stuck in some kind of purgatory where Shuramud is an oppressive god of death who has doomed them to eternal hard work.

After a while, the other workers urge them to steal their weapons back and organize a revolution against the guards. While this revolution will eventually fail, the player characters will learn more and more about what is actually going on in this world and that the sunset tower that is being built here is part of a plan to end the eternal night.

Act 2: In the service of the sun god

Once the player characters have had some time to get used to their new environment, learn the language and customs of the locals and find out that the Shuramud cult is not evil but just desperate, they slowly gain the guards' and priests' trust. They are offered some freedoms if they agree to help the cult's cause.

For now, they are tasked with protecting the workers from monsteres, to steal supplies from a nearby village occupied by Iwaspat's troops or to acquire an artifact that's needed for the new temple from an old ruin. As soon as they have proven their loyalty and competence, they can start to prepare for a journey along the great river. Disguised as merchants, they will scout the realm and build up resistance cells.

Acts 3 to n-3: An arduous journey

This part is very much a work in progress. I don't even know how many acts this will be in total, so I won't go into detail for now. The player characters visit several important locations in the realm to learn more about the world, make new allies, sabotage the Iwaspat cult and gather resources. They find out that the leaders of Iwaspat's cult want to install one of their own as the new high priest of Shuramud to eventually unite both ruling dynasties (more about that in an upcoming politics post)

Act n-2: The fire ritual

By now, the Iwaspat cult knows about the sunset tower construction site and is gathering its troops for an attack. Even with the new allies that the player characters found, the Shuramud cult's defenses probably won't hold. There is one last thing that might save them though. In rare cases, when someone whose life was dedicated to Shuramud dies, their soul will turn into winged fire elemental. The player characters have to help develop a ritual that lets believers sacrifice themselves to trigger this transformation on purpose.

Act n-1: Siege at the sunset tower

While the newly created soul birds face the attackers head on, the player characters need to fight their way along the flank to eliminate an enemy general.

Act n: Dawn

The sunset tower is safe for now and construction is almost complete but at the same time, Iwaspat's follower now know what's coming for them. It's time to infiltrate the capital and depose the false Shuramud high priest. By now, they should have realized that eradicating the Iwaspat wouldn't be a good idea. They will need to find a way to create a true balance, the world sees its first moonrise and a sunrise will soon follow.

I'm not sure about the details of this balance yet. The title of high priest for both gods gets passed by a combination of inheritance and divine trial. I'll go into more details in a post about politics and government but maybe there will be someone who unites both bloodlines and act as a tie breaker when the high priests of Shuramud and Iwaspat can't agree. That would fit the moon symbolism pretty well.

That sounds like a fun setting. I'd try to have factions within the followers of each god. That gives you the option of having both provide quests and sympathetic NPCs.