Hello Peoples

I've been pondering on a problem that has plagued me these past few weeks being a GM for a Rogue Trader group, the main theme and story of this campaign is finding a legendary world rumoured to have lots of archeotech technology/history.

Obviously finding a thing is not accomplished by simple investigation there will be dynasties and major secret imperial organisations going to come to blows with the group finding this thing. My question is, what would be a suitable megastructure that hasn't been done too much, is not a major 40k canon break but also very rewarding to have found for the group.

I know in 40k there's talk of a dyson sphere trapping a C'tan, a forge world that's almost hollow and obviously many weapons that can blow up planets and stars, so what's wrong with another stellar/planet megastructure.

Any ideas would be appreciated since this the major plot.

You want something big and stellar. Is this something the end of your campaign or will the game go on afterwards? This is an important point as handing the players a mobile world-killer is a game changer IF the game goes on afterwards 

Things that come to my mind:

1) A large “supply cache” structure from the early days of the Imperium, or even before that. Think of this as a multi-level dungeon, complete with traps and actual ROBOTS guarding it. Bad thing is: the whole structure is largely unpowered (with the defense systems having their own internal power sources, and yes: some of them still operate). Unbeknownst to even the founders, a “Schismatical” (see DH1st “Creatures Anathema”) slipped into the lower levels. That is why a sect inside the Mechanicus (Thule?) wants to make sure nobody reaches that world ever again. So they might themselves have forgot why. This allows some salvage but keeps the whole complex from being salvageable.

2) A dead Eldar Craftworld that became an unsanctioned human colony. The reason why the Eldar do not reclaim it? The whole thing is tainted by Slaanesh, deep down into the wrathebone core. You might already guess what happened to the colony that was erected in its remains, the one that was meant to study and salvage the **** thing as a source for artifacts

3) A space station formed out of a cluster of former settler ships in an orbit over a fertile planet. The majority of the drives have been dismantled for other parts but the construct is still populated. And in league with an xenos group of your choosing (perhaps these strange RT trader-aliens the elder hate so much?). The humans on the ship cluster have erected themselves as GODS over the humans down on the planet (who are feudal Europe people with advanced agricultural technology) who give them “sacrifices”…the Imperium in a nutshell, so to speak. So, when the RT want to take “the price”, they will have to deal with this micro-empire an their allies.

Cool those are some interesting ideas, and yes this is something coming to the end of the campaign, the rumour according to the group is that it is a archeotech world, so the rumour could be an overstatement or it could be the truth and it is a lost world.

If you can think of any other ideas involving such a late/ campaign final thing that would be awesome!

I do like the strange structure you mentioned which could have unknown purposes and something scary hidden inside.

(...)

I do like the strange structure you mentioned which could have unknown purposes and something scary hidden inside.

Point 1), the "supply cache"? I had an idea like that after I have read about the reasons for "graveyard worlds" in the Imperium: during the crusade that later had the Calixis sector come into being some planets where used as "burial ground" for the millions and millions of fallen of the immense war effort. Everything in 40k is mega-big and highly illogical (why not bury or burn the dead on the world they died instead of shipping them across DURING WARTIME?). So I thought about some kind of automated supply base. Again, "mega-style".

The surface level would have been hangars, loading bays, air defense and the like... and now in ruin or not eve present anymore. The lower levels might have been simply elevators and hoists (two to three levels deep) and additional armor. Further below, there is a level that is security and defense and perhaps the storage of fighter crafts to answer an attack etc. Below this, there would be storage areas..vast. Both for material and men. Even lower there could be medic bay and fabricration areas (wounded soldiers and raided material are brought here and turned here... to fashin the next company or regiment of soldiers.... or stuff the supply base needs itself. The level below that would be staff, energy, logistics etc.

Other ideas:

The whole affair is in truth a hidden base/hoard of former RT who robbed surrounding system and stashed thing here in a hidden base. As he never returned, the base was left to fend for its own.

An automated, moon-sized war-weapon of an alien race. When it is discovered and salvaged, it re-activates. If the re-activation isn´t stopped, it will set course toward the Imperium, destroying even world with humans on it. Do you RT have colonies....? The re-activation might take days, so. On the other hand, the identification and removal of the systems that power the war-world might take more than just days... and there are alien warbots re-activiging within hours....

x) Terraforming

The world itself is not special. Useful, yes... but not special. The interesting thing isthat mountains-sized atmosphere-transformators have once been installed here that have cleaned the planet of everything that is hostile to human life. If one could study, re-activate, dissamble and ship these mountain-sized units any hive world would pay FORTUNES for it... or be willing to engange in long-term contracts. But the native now-tribal populace must be questioned for further ruins or secrets, as one must find out how these giants worked back then!

Well that station idea could be useful as a what if encounter from a bad warp jump.

Hah! a Moon attacking the Imperium, that's definately a sense of "Oh we messed up big time!"

so far I've looked into other megastructures and the list is

A halo ring

a hollow moon dedicated to some big project during the dark age of technology

any of your ideas

Any else want to contribute please do so

How about a DaoT processing/construction module? Twice the size of a Ramillies class starbase (and like the Ramillies, lacking warp engines), it was the core of a STC shipyard, stripping asteroids down and processing the ores to produce hull plate and structural beams but NOT components (materials were taken to other modules for that). By itself, it provides a bonus for hull repairs or can construct bare hulks of a couple of ship classes (perhaps up to cruiser size), but if the players were to find suitable STC data different ships could be built providing they have a source of components. This also sets up a quest for the component construction modules and a serious rivalry with the Adeptus Mechanicus...

If you place it in a system that has been stripped of resources, they also have the fun of trying to move it to somewhere that it can be used.

What about other potential DAOT (Dark age of technology) places, like experimental projects or artifical megastructures that even then could be considered highly special projects, or heck research facilities.

I only ask to encourage even more ideas, since the group I have is very interested in something that's never happened before.

Kemplerer rosette - small dense moons orbiting a central point away from any heat source because the industry present on those moons already generates too much heat (think Pierson's Puppeteers). The moons are dense because they contain a huge amount of minerals to feed the industries. The whole thing orbits a black dwarf, or a white dwarf so burned out that it can't be seen from greater than a few light years away. Put anything else you want on it.