So for a while now players are fighting tyranids on castobel and since i decided to change the scenery what is most logical course of action? Since IG don't travel much and usually fight till enemy dies or they die i need ideas how to make sense of this transistion. I was thinking that they will be picked by inquisitor to be his/her accolytes but that makes it dangerously close to dark heresy (which i am not sure if it is a bad or good thing). Another idea is to get them loaned to one of rogue trader and be part of his crew (one of the players would like to pilot viodship others just would love to do ship boarding) or get picked for some kind of admech/rogue trader expedition and lastly i was thinking of some kind of clerical error that the regiment despite raging war on castobel get transfer to another system to fight chaos/orks/xenos. Any thoughts?

Change the situation on the front. Due to massive casualties ground forces are evacuated and planets are cleansed from orbit. Or the hive fleet was scattered in a massive void battle and troops are sent to different battles while local PDF finishes off the remaining disoriented organisms

Get them to a fairly safe place. FOB, trenches etc. Then Chaos/Tau make a major moves. Regiments are needed on the double (specific reason for their regiment depend on the type), so since they're in a fairly cold zone, they're picked.

Hmmm... You seem to be focusing on getting people off planet.
How about trying to bring the fight you want...To the planet?
I mean, orks coming down to pick a fight with nids is not unlikely. Having humie guardsmen there would just make it all the better in the orks' eyes. Bigger fight is allways better.
Maybe chaos worship start surfacing in other regiments as they get desperate trying to survive against the tyranid threat.

Offcourse, if you want to change the scenery your players are fighting in, then Chaplain and Drath have provided good options allready, on how to get off planet. So... Yeah, i got nothing...

Good luck finding a solution!

I like Cortezz' suggestion. If you have your heart set on your players getting off planet, a solution would be to withdraw the regiment after heavy losses (perhaps with a session in which their location gets overrun by tyranids....).

The regiment is to be reorganized, merged with another depleted unit, rebuilt with fresh drafts or sent on punishment detail because it lost the previous battle or given a period of R&R to recuperate.

While this is going on, they are attacked by the new enemy in the new location or a sudden crisis erupts and your regiment is the closest IG unit and has to respond....

Personally, i'd have the regiment withdrawn to be merged with another depleted unit (scope for role-playing tensions and who's 'arder scenario's as the new combined regiment settles down [think ciaphas cain] or filled with fresh drafts (scope for role-playing veterans vs. impressionable noobs). Add 1 or 2 sessions with some mystery like an officer acting strangely because he was infected with the genestealer gene etc.

And then move into the new campaign with a new enemy. Preferably something that feels, fights and acts very differently to tyranids like eldar or tau. Perhaps an eldar location has been found and must be destroyed immediately. Unfortunately, it is guarded and after initial success, the IG face an escalating threat as more and better eldar troops start appearing to retake the location.

Or perhaps the tau have sent a scout force to a planet and the IG regiment is ordered to hunt them down and any collaborators amongst the human population.

As indicated earlier in the thread, you could certainly have new enemies/challenges come to you. Your regiment could be re-assigned due to mass casualties. The fact is, as the military arm of the Adeptus Terra, the Imperial Guard is beholden to the their will alone. A change of scenery can be the simple result of a change in orders. Typically, yeah, the IG is stuck in a battle "til they're dead, or we are..." That is hardly set in stone, however. The needs of the battlefront are fluid and may change, depending on the needs of Command. Your regiment's skill set may be needed elsewhere. More bodies are needed on this planet over here to stave off the orks. The locals are restless over here. An influential Colonel doesn't like/want your regiment's presence here - ears have been spoken into and suddenly your regiment is pulling garrison duty on a plague-infested waste reclamation world... As the GM, you can have the regiment go wherever you please. Ideally, all you have to do is make it believable. You don't even have to be logical. "Alright, boys, we're wheels up in 50. We're reconning Gort's Hiney." "But Sarge, isn't that a corpse-starch processing plant? Like on an asteroid, eight worlds over?" "Why, yes, Trooper, it is." *glares* "New orders from on high..." "Bbbbut Sir? We're a day from routing these heretics....?" "Yes. And? The Departmento has spoken...." Coz the Departmento never makes mistakes, right?

They are His Will. So questioning them is questioning Him. So that's heresy, right?

HERESY!? *BLAM*

Thank you for replies. Now i have an idea how to do this. Since it's on Castobel I will launch major tyranid offensive on their positions, order them to fall back show them what carnifex do to tanks and decimate half of their regiment. When they will think all is lost space marines drop pods will hit the ground and rout tyranids. "we take it from here son" kind of scenario. Then high command will decide that they are not needed anymore since castobel reborns regiments and marines can take care of tyranids.

Now i just need a believable transport out of system. I was thinking something like rogue trader vessel which was "politely" asked to deliver regiment to other sector or maybe a navy vessel but i am not sure how navy operate and if they would commit a voidship to deliver one regiment to the other half of galaxy.

Another thing i need and maybe some of you will help me since i lately lack some cool plot ideas. I need some general plot involving chaos or eldar, some kind of intrigue. Something that is more than random missions my players had so far like take communications array sabotage this, scout that, extract HVT etc.

What kind of intrigue did you have in mind? Tzeentch cultists are perfect for all things schemey and convoluted things. It depends entirely on the scope.

Transport out-system should not be a major issue. Maybe if you were in a more civilized sector, it might be an issue. Asking for aid from an RT is more the realm of a resource lacking/undercover DH team. The IG doesn't typically ask for transport. They are military with objectives. Hitching a ride is counterproductive and so gauche. Seriouusly, there's enough traffic in the Jericho that getting a troopship should be pretty standard. The Army and Navy DO have longstanding grudges but not every transition of assets is a drag out fight b/w the two. If it were, Jericho would already be 'nid nibblies. It's tangible tension, but cooperation is a necessity.

As for intrigue, why not look into having the Eldar be creeping about? Maybe something is going on at a human held world that turns out to be a Maiden world? Maybe a Craftworld is floating on the edge of the system and Rangers are infiltrating said world, looking for something that could have dire consequences for the population? A mystical power source? A lost Avatar of Khaine? A powerful farseer in suspended animation? An army of buried Wraithguard, corrupted by stasis and long proximity to humankind? Hope these might be useful in poking the creative flow....