Right... The big problem with saying "you can do whatever you want" is that suddenly, people can't think of anything to do!
Equally, most people aren't really megalomaniacs - and those that are, don't play well with others. As a result, getting a campaign started comes with complications. Particularly because the rest of my players are all staunch Imperial types.
So, I decided to take a step on from Deathwatch, and do Deathwatch in reverse. To explain; the campaign will be set in the Jericho reach, but from the other side. Specifically, to give the players a 'being the good guys' goal (sort of), I'm putting them amongst inhabitents of the reach (specifically of what was once Calitar sub) and letting them see an Imperial crusade from the other side (queue vast, faceless tide of genocidal, pyromaniac fanatics intent on enslaving or destroying every free world in the name of a dead god).
Timeline-wise, I'm setting it just after the battle of Khazant - so Tiber Achillus has just taken down the reaver-world which controls the bulk of the free forces in the Jericho Reach, and his commander, Ovidius, is pressing closer and closer to Hadex and the Charon Stars.
It's something of a "you will unite or you will fall", moment, which is an interesting one for the forces of chaos (who really don't play well with others). The one man who might be able to unite the scattered, shattered, warbands into an alliance that might - just might - be able to stop the Imperium is a cult leader called Elak Sarda.
The players have either signed on, or been drafted into, the nascent Stigmartus and are trying to ensure that he manages just that - fighting delaying actions against the Imperium, bribing, begging, bullying or butchering other factions until they sign on with the Covenant, and so on. Essentially, an alliance of rebels (sorry, renegades) fighting the evil galactic empire (sorry, imperium). I don't intend to put the as Sarda's right hands, but by the simple fact that they're either marines or of a similar level of power and influence, they're going to be fairly important.
Trying to think through compact ideas - the early Stigmartus definitely need to get the Cyclopean Congregation and one or more of the Forges of Samech on-side, along with creating the Stigmartus forces, and getting as many warbands of astartes to aid them as possible (the word bearers and the pyre, plus any assorted people who'll listen - like my players).
May also translocate several of the cooler locations in the screaming vortex into the fringes of Hadex. The Ragged Helix always struck me as an awesome concept.
Any thoughts for missions or important character? Campaign Suggestions?