So as my current game is nearing its middle point I've been asking my players as what they want to do next. Most votes have been in something single chapter, one person even suggesting playing through the Space Hulk board games missions.

So I was wondering if anyone has experience running as an all the same chapter, I've been toying with the idea as even starting them at higher rank/renown as running as a Command Squad as to keep it from being a full tac squad, or even starting them as scouts and going through that way.

So big question is has anyone tried this and if so how did it play out. Thanks in advance

One of the challenges with single play is that you lose the "everyone is equal" and the cohesion mechanic becomes weird.

Since you're all from the same chapter then one person is going to have rank over everyone else. Orders become orders not suggestions like the KT leader.

The cohesion mechanic is supposed to represent different chapters coming together and having challenges. Without that conflict, the team cohesion should skyrocket. How much is up to you.

you lose the "everyone is equal"

I assume you meant "everyone is unique", in that every PC comes from a different culture, so to say?

If so, that could indeed be a hurdle, though not one that is impossible to overcome or may indeed even bother the players. If they just want to have fun, they likely won't even notice this, but if they are veteran roleplayers they will probably come up with personal backgrounds that will still make each character feel like a proper individual rather than a cardboard-cutout. I recommend focusing on past battles where the character may have done something special, as well as perhaps a slight inclination towards some sort of hobby that is not inappropriate for the monastic lifestyle of the Astartes (such as reading specific scripture and poetry, being a Chapter history nerd, or doing extra hours in the close combat training hall).

Since you're all from the same chapter then one person is going to have rank over everyone else. Orders become orders not suggestions like the KT leader.

Ideally, this really shouldn't be a problem. When my group played DW, we used Games Workshop's original background for the Deathwatch, and so we had a fixed command structure with a Captain leading the squad. Worked fine for everyone - after all, just because you have one guy being the boss doesn't mean he no longer is open for suggestions from everyone else. Indeed, having someone with the authority to just order which idea to run with rather than deciding it after a long debate between equals may speed up the game.

Other than that, my personal recommendation would be to ask the players what sort of role they would prefer - however, I feel a suggested standard should be a normal Tactical Squad from one of the Battle Companies, simply due to narrative reasons: This role allows the players to show up in virtually any scenario and supports almost any type of character class, whilst simultaneously having them start out "low enough" to be able to still make a name for themselves and earn their fame, as opposed to having them begin play as top dogs already. You could fill up the rest of the squad with NPCs by either using Minion or Horde rules, or perhaps jury-rig Only War's Comrade mechanic into the game.

I'd limit class selection to Tactical, Devastator and Assault Marines with an option for an attached Apothecary. Squad leader should be a Tactical Marine. Depending on the specific scenario, you might be able to smuggle in the other classes as well.

For example, you could have the campaign start them as marooned survivors on a drifting Strike Cruiser during a failed invasion. The players have to clear a way to the hangar (fighting enemy boarders in the process) and then take a Thunderhawk to the hostile surface, where they have to find a way to contact the Imperium and organise their pickup, all the while fighting a guerilla war against the native defenders. If it's a human world, perhaps they might even link up with a Frateris Militia resistance cell?

Alternatively, how about a sort of Honour Quest? Perhaps the players have somehow been disgraced and now have to regain their honour through some sort of adventure. Effectively "exiled" from their Chapter, they would be like medieval knights-errant, perhaps hitchhiking a trip on a Rogue Trader's ship - and helping him/her with something in exchange - to recover a lost banner or an important piece of armour from a Marine that had to be left behind during a hasty retreat, etc.

I did mean everyone is equal in standing. In death watch the KT leader is the "first among equals."

If your group is set up to have a hierarchy more power to you. Have fun blasting those Xenos. I know my group wouldn't handle that well.