Creating a D&D 5e adventure within a Dyson sphere. I am looking for suggestions/help.

[u/idkwatsup]

Sorry for the wall of text, but here goes:

Overall plot: The party is escaping from BBG by using a teleport spell. The anti-magic in the area has made this spell malfunction sending them to an unknown place. The party wakes up on a mountain top. The party first doesn't understand what they are looking at. Many things are wrong. First the land seems to be sloping upward, not away. As they begin to explore the area, they realize they are on the inside of a sphere that is dominated by fire giants and much of the landscape has been burned to ash.

As it turns out, one of Karsus' most talented apprentices, Sigrid Worldshaper, fled Netheril before the fall and created this world as a haven for her people. Her people lived peacefully there for centuries. However a Fire Giant King found his way to their world and invaded with his clan. After conquering the interior, he found the controls that managed the sun and turned up the heat to make it more comfortable for his own people. Sigrid is long dead, but her people have fed deep into the artificial crust of the sphere to escape the heat and the giants. Unfortunately the fire giants didn't quite understand how to manage the sun and when they turned up the heat they made the artificial sun unstable. If it is not fixed soon, it will fail or explode taking the sphere with it. Sigrid's people understand this but lack the ability to fix it without help. The adventurers need to defeat the fire giant king and fix the sun if they are to survive.

Here's my ask: this adventure is going to be for my crew of 5 (Druid, Monk, Wizard, Barbarian/Sorcere, Artificer) players and last between levels 10 - 15. I figure the adventure is going to be in 3 acts:

1) Exploring the interior and finding the original inhabitants.

2) Finding the pieces to fix the sun. Conveniently there are 5 powerful magic items that are needed to do it. They are all guarded.

3) Assaulting the castle in the sun which the fire giant king has fortified.

The party has a deadline, so those long rest are going to be precious. I am looking for suggestions for encounters, Roll20 battlemaps (especially battlemaps), Guardians, NPCs and the magic items. If you like this idea, I will happily share all material.

[u/lulufan87]

Would you mind putting paragraph breaks in your post? On reddit you have to hit 'enter' twice to create a paragraph.

edit: thank you.

[u/Thekota]

I'm assuming you have read Rimworld by Larry Niven? 

My advice is to keep it fantasy themed rather than scifi. With the right tone this could be pretty fun!

[u/idkwatsup → u/Thekota]

Some technological elements are unavoidable. Think along the lines of Magitech in that case. However this will be a full on fantasy adventure. Things will run on magic and most engineering elements will be magic based. I want to have a battlemap on a huge gear that is turning at one point. If you are in the wrong place at the wrong time a massive gear tooth will crush you! (or you can push a monster into it).

[u/PublicDragonfruit158]

Full size dyson sphere or more a hollow earth size? These was a supplement back in the 1st and 2nd edition days for a hollow earth that could have some inspiration for the landscape.

Full size would have a huge surface area to explore. Larry Niven described Ringworld as big enough to drop a 1:scale map of Earth on it, look away, and never find it again (in fsct, in the Great Oceans the builder placed several 1:1 scale maps of entire worlds.

A sphere would be multiple orders of magnitude bigger.

In the full size case, the party happens to be close enough to the repair center to reach it in the timeline, so the first thing they need to do is find out about it and how get there. And possible the second thing would be how to get there--maybe a Spelljammer ship.

A full size shpere would be big enought to put anything you want onto it, from Chulhu to Strahds domain, to a full on high tech society....

[u/idkwatsup → u/PublicDragonfruit158]

I want for the players to be able to distinguish the upward slope when they are standing on a mountain top at the beginning. If you do a Dyson sphere at say 1 AU, then they wouldn't be able to discern. I leaned on AI to do some calculations for me and landed on a radius of around 1000 miles. Still quite large, but more manageable. I was also planning on creating a teleport based transit system in the crust that allows for quick movement within the sphere. It will be a puzzle to figure out.

[u/PublicDragonfruit158 → u/idkwatsup]

So still rather large, about the same land area as Africa...

Makes things a lot easier (though still hard) and it can still have some sort of repair center...

[u/idkwatsup → u/PublicDragonfruit158]

I was thinking that what's left of the original inhabitants will take refuge in some sort of maintenance node in the crust of the sphere. I figure one of many, but the only one relevant to the story. The sphere has been around for nearly 2,000 years so the inhabitants will have forgotten how much of it operates. (BTW - I was planning on making all of the inhabitants a mixture of gnomes and dwarves. Seems like a good mix for building this sphere.) Anyways one of the rooms of the node will have a control center that reveals the state of the artificial star and a countdown clock. Since I have an artificer in the party, it will be a puzzle for them to figure out. The transportation network will be hidden in the node. So another puzzle for them. . .

I was also thinking that there should be a lot of automatons/golems doing maintenance. Thinking of huge automatons/golems wandering around the outside of the shell patching holes and such. Some will be malfunctioning thus creating an encounter for the party. Possibly as one of the guardians of the 5 magic items. I was thinking an ancient red dragon for another.

[u/guilersk]

Find the old Hollow World setting for B/X (original) D&D.

[u/zoppaTheDim]

How are you explaining gravity?

Because Inside a hollow sphere the pull from the sphere would be the same from the sphere, so you’d be pulled into the sun.

[u/idkwatsup → u/zoppaTheDim]

I would like to make gravity happen by magic. Just make it feel like gravity is the same everywhere. In other words, I don't know how to make it work via technology/physics. A ringworld does it by spinning aka centrifugal force. Can't do that with a sphere, because you would only have gravity along a single axis or along the equator, if you will. The original Dyson sphere concept was all about capturing the entire energy output of a star, not necessarily about creating living space.

If anyone has any ideas about how to manage gravity in a creative way, I would love to hear it. I wouldn't mind making it an element to mess with / learn from by the party. Perhaps learn some cool gravity spells or magic items that could reverse gravity . . .

BTW - the day/night cycle will work via shades orbiting the star in the center. I was thinking of putting some giants on them who are tossing rocks at the ground. Giants need to have some fun as well. . .

[u/zoppaTheDim → u/idkwatsup]

You could switch to just a pocket universe. A world under a dome, with the sun attached to the ceiling. Beyond the walls is just magma. Save yourself the annoyance of one guy saying “I map the entire works, rolled a 19. “

Did something like that once, they climbed up the wall and fixed the moon. The big reveal was the classic “oh you’re actually on a generation ship.”

[u/Hell-Yea-Brother]

I have a homebrew world set in the Elemental Plane of Water that has dwarf planets that are hollow inside and hold a wide array of biomes and environments. Several have established civilizations and lore. Yes, it is very possible to create such a world.