Hi there!
After some time fleshing out my ideas for an Ordo Xenos campaign I think that I have a working formula for it and will post it here for some peer review. My thoughts on it is that I'll get the basics hanged here before I try and go into details or stat out NPC:s and stuff.
Setting: An Imperial world that is has some advanced machinery guarded by an enclave from the Adeptus Mechanicus, the most important is the local Spaceport. Otherwise the technology is mostly in the civilian department in the 19th century style. The planet is populated by mostly humans with a caste of Untouchables in the form of mutants who are either worked to death on plantages and in certain base industries or mostly just trying to stay the hell away from the humans' law enforcement unites.
The planet is divided between the old nobility, in style like 19th century American gentlemen while they are challanged by the growing power of certain merchant houses, guilds etc. who are more akin to the 19th century industrialists of Europe and America. Beneath them are the serving majority that works on plantages, industries and similar. Its far from the more tyranical Imperial planets but hardly a place of freedom either.
Main antagonist: is a Rouge Trade and Xenophile under alien influences who is deeply involved in the Cold Trade and is the single source of supply for alien relics and weaponry to the planet. He also smuggles aliens onto the actual planets for the right fee. He is a brazen man with a considerbal arrogance and a dozen bastard children sired on his crew members. His crew consists of mostly Void-born and a few Xenophiles and anti-Imperial fugitives. The more outstanding members of his crew are the following:
* A renegade tech-priest and heretek who uses Xeno-tech in forbidden ways and have even made Xeno-tech implantments into himself and some of the Rouge Trader's crew members.
* A Xeno-hybrid that is the result from the tech-heresy of making a union possible between and alien and a human. It looks mostly human but with some changes and with an utterly inhuman mindset.
* A Xenophilic scholar who loves and admires the ways of Xenos far above that of mankind
* An anti-Imperial rebel fugitive who is ever ready to strike against the hated Imperium
* A Xeno-tutored psycher governed by strange taboos, bans and commands imprinted into the mind during the aliens' training
* A Navigator who don't think himself as human but surrounds himself with a small court of mutants and similar foul creatures, some of them having been the subject of the tech-priest's Xeno-tech experiments.
So that's the major opposition that will challange the characters during their investigation on the planet. My main idea for investigations is that they will eventually lead to information regarding the Rouge Trader and his identity itself. This would then lead to a final show-down against him and the Acolytes can break the main source of Xenos-related problems on the planet.
Stuff to investigate
* A mutant cult that is following a mad prophet calling for all to join him in service to the Grey Angel and tear down all the humans for a world where the mutants should be elevated in glory over their oppressors. The Grey Angel is of course a Xenos and a member of the Aeryx species (which is one of my own creations). The prophet has been smuggled to the planet by the Rouge Trader to make some basic work for a eventual establishment of the Aeryx themselves, and they are gathering resources to buy weaponry from the Rouge Trader and local amorale arm's dealers, as well as recruit as many mutants as possible into their ranks.
* A noble that has in his possession a mask taken from Xenos ruins that grants biological immortality but with some hideous draw backs, which I've yet to determin in detail. He bought this mask from the Rouge Trader because he wouldn't want to die of old age and so is isolating himself in his mansion. I was thinking of maybe changing it to a Halo Device, but I feared that it might be a bit to powerful for a fresh band of Acolytes to tackle.
* An lower Arbiter officer that owns a Xenos blade he uses to keep the local mutants in check, and he is protected by his extremely loyal comrades. He confiscated the weapon from a mutant, who had gained it from the Rouge Trader, but the officer decided to keep it rather than leave it ini order to turn the weapon of the enemy upon themselves.
* Some nobles who have bought a few reliefs and statues from Xenos ruins from the Rouge Trader for the prestige that it would gain them among their peers. These things are not dangerous in themselves but will lead the Acolytes on the trail of the local Cold Trade.
* A man who lost everything to the Imperials because his brother turned out to be a heretic, and driven over the edge decided to dedicate the rest of his life to vengeance. He uses terrorist tactics to try and kill as many Imperial officials regardless of civilian losses as he can. My idea is that he'll get on the characters' trail at some time and follow them and try to kill them since they remind him of the Acolytes who killed his brother.
* A heretical preacher who have formed a heresy which says that the Emperor intended for mankind to co-exist along with selected species of alien races. They are at present starting to recruit beyond a small circle, seeking contact with the Rouge Trader to get their hands in Xeno-tech and making direct contact with aliens to make their judgment if these are intended by the Emperor to live along with humans.
* An alien bio-construct that have been created by a race of Xenos to act as a replacement for a abducted Imperial official. This bio-construct in itself does not have any other purpose than to mask the abduction at present, and thus operates with the victims memory and personality implanted into it. Other constructs of similar design can sometimes be employed for infiltration, spying or assassination by these Xenos, and thus the Inquisition would dearly like to see it flushed out and captured before any hidden commands implanted into it is activated. While it looks just like a human, its internal physiology is entirely different and its thin white ichor which is has instead of blood is probably the part that is most easy to detect. The aliens were aided in getting to and from the planet, by the Rouge Trader.
* A smuggling ring that is buying stuff from Ork pirates and also selling the greenskins fuel, ammunition, weapons and other items that are used to harm the Imperium. This smuggling ring is actually headed by a bastard son of the Rouge Trader and they have close contacts with the Rouge Trader himself.
* A rouge psycher who lives the life of a bandit but mostly just wants to stay alive in opposition to the Imperium's demand of his destruction. The problem is that he murdered a woman with a trinket that turned out to be a Xenos artefact which became activated by the psycher's attention to it. The trinket was sold by the Rouge Trader and its feared that it is cultivating Alien influence over the psycher's unprotected mind.
For back-up another Inquisitor also has a band of Acolytes on the planet that can be contacted, but only at the price of a future favor to those Acolytes and the ire of their own Inquisitor who is on bad terms with the other Iniquisitor. He/she certainly don't want his/her own Acolytes to own favors to the Acolytes of his/her rival. This is mostly if they really get stuck with something and their own contacts and allies fails them.
This is some basic idea I've been playing around with. I've yet to decide the details regarding the Acolytes own Inquisitor but most likely its a somewhat more Puritan than Radical, but not among the extreme Puritans. I'm mostly thinking of keeping him/her relatively aloof and secretive at the start.
Ideas and comments are welcome.