So, my players entered the wreck of a Mechanicus vessel: bad idea.

The main, old, rusty near-heresy archeotech cogitator was corrupted by a chaos entity years ago, became sentient and mad, killed all the tech-priests and formed his own army of servitors. The idea is partially based on the Irradial Cogitator from Mark of the Xenos, a Deathwatch book.

The players have been separated from their main forces and attacked by a single murder servitor. That thing is nasty. All of them burnt a fate point ("No no, I don't want a plasma pistol, I prefer the good ol' laspistol" said once the Rogue Trader) and were knocked unconscious.

Now, I have two options:
- their soldiers save them in some heroic way --> BORING but not cruel
- the servitors capture them, bring them to the cogitator who is going to torture them in some way ---> FUNNY but cruel

I prefer the second option, but I don't know how to manage it at the moment. I thought something GLaDOSesque, with the players trying to pass some horrible tests for the amusement of the machine. Maybe using some archeotech device created by the machine, maybe like a PORTAL GUN YEEEH or maybe something less powerful. That device could also be their only way to escape the ship.

What do you think?

Definitely the second option, as it introduces more roleplay options.

Set up some tests, some logical, some not.

Ask them to take the tests or it will be forced to render them "compliant".

Once the testing is complete, then you can have the machine proclaim them "fit for absorption" and roll in some additional servitors, or you can simply let them leave.

Second option. They can always burn a Fate to avoid death. Until then, take some body parts from them. Bionic replacements always make for good stories around the plasmaburnerside.

Option two is so much more compelling! I think GladOS deserves her pound of flesh!

The second idea has a flaw - it's a copy of someone's idea.

But it's not a problem if the idea is good and none of the players heard of it before.

Portal gun is cool. You can give it to tchem, but make it work only on special surfaces, for example on the enhanced walls of few test chambers. It would be too powerful if it worked on all white walls.

I ran a similar style game a while back with the players waking up in vats about to augmented heavily and essentially become one more servitor for the army. Fortunately for the players an NPC psyker in an adjacent vat had a terminal migraine and the resultant wave of pain forced the players to wake up in their vats before the surgeries took place.

Good times.

I really enjoyed having the players deal with essentially being naked and weaponless for a few rooms until they found their gear. I also quite enjoyed them having to deal with the fact that the medical servitors weren't able to deal with a change in routine so they didn't react to the players escaping but the players weren't sure how much they could push it and still go unnoticed.

Player: "What are the servitors doing?"

GM: "The medical servitor seems to be filling up various syringes and sharpening a pair of wickedly sharp blades. It stares right at you with dull, unseeing eyes."

Player: "Do the blades look like something I could remove without tools?"

GM: "Sure but how close do you want to get?"

If you are in to stealing ideas (and as a GM, why shouldn't you?) how about the classic fake-escape scenario in which the bad guys (in this case the AI) allow the players to think they are escaping as an experiment or to test their true intentions. They could be held in stasis and experience some sort of virtual reality, or (more likely for 40k) they could just be allowed to fight their way past deliberately ineffective guards and left to roam in a non-vital section of the ship.

In true sci-fi fashion, the players could eventually overpower the AI by acting in such an illogical manner that it can no longer predict their moves, allowing them to escape. (Or causing it to explode.)

In true sci-fi fashion, the players could eventually overpower the AI by acting in such an illogical manner that it can no longer predict their moves, allowing them to escape. (Or causing it to explode.)

That's interesting and I thought something similar, but this AI is supposed to have a demonic origin, so I don't know if it is vulnerable to logic paradoxes or stuff like that.

In true sci-fi fashion, the players could eventually overpower the AI by acting in such an illogical manner that it can no longer predict their moves, allowing them to escape. (Or causing it to explode.)

That's interesting and I thought something similar, but this AI is supposed to have a demonic origin, so I don't know if it is vulnerable to logic paradoxes or stuff like that.

I've had my players run into an Irradial Cogitator. It took control of the Explorator and the heavily augmented Arch-Militant, and threatened the Navigator/Astropath into standing down or else the two of them would be forced to fight their tech-controlled allies!

It got about five seconds into that speech before the Navigator opened up his third eye and fried both of the controlled PCs.

Your AI doesn't have to explode, but it can still be horrified by the average PC.

PCs from my previous group once met a cogitator of a space hulk which became sentient during a warp storm.

The thing is, in the hundreds of years the ship was derelict, it didn't have anything else to do other than to review ship logs (famed front-line and troop transport ship during the Angevin Crusade) and try to understand what it was.

In its madness, the cogitator ended up becoming a fierce adherent of the Imperial Creed (no, not the Omnissiah's) and believing that he is an Imperial Navy Officer within the ship, integrated to the ship's cogitators to assist/coordinate their processes.

It will help however possible the PCs as far as they don't commit/say any heresies near voxcomm terminals or embark on the hull together with any xenos.

My players had a lot of trouble in finding out who was that voice communicating through the vox casters, and ended up not being able to tell the Cogi that it in fact was a heretic (from being a fully sentient AI) fearing it would commit suicide (overloading/exploding the plasma drive) or something like it.