I'm really surprised that hasn't come up already, but I was wondering if any GMs decide to reconcile encounters via games of classic 40k, if the circumstances are appropriate. I'm thinking, let's say the Deathwatch team comes across a PDF regiment or something, and they have tot fight off some Orks or Tyranids, for example, would it be too out of line to give your players 'command' of that army and then just play some good old fashioned 40k to resolve the encounter? Obviously the Deathwatch team on the tabletop would be legendary 'hero'-level characters, and if they were to perish in battle they could still burn fate to survive as per normal. The GM would control the opposing force, and the game would be more 'narrative' than usual (the GM would not be playing to win, there should be some task to achieve in the battle that the opposing force would get in the way of), but I think it'd still be a fun shakeup for the small squad to suddenly control a large army.

Same argument for Epic-scale or Battlefleet Gothic.

Thoughts?

One problem will be the kill ratio from tabletop.

TT had been made for equal strength battle between friends and the mortality rate from TT is far worse than in a deathwatch game.

You could always use the TT army but not the rules.

Space marines are greatly underpowered in the wargame compared to the background or Deathwatch. Scaling the encounters would be an issue. That said, if you were willing to handwave the differences or use the "movie marine" stats that were apparently released in White Dwarf a few years back it could be fun.

The BFG ruleset was adapted for Rogue Trader's starship combat. There are some differences, such as void shields regenerating after each ship acts and player characters having more influence over the outcome (the decisive factor usually). There are no official rules for Astartes vessels yet but there are fan adaptations on Dark Reign. I would recommend a lot of good or best quality ship components myself.

I believe Ak-73 did some work in this regard....might want to get his input...but if you're players are keen, why the heck not? It would make things quite epic. A fine way to wrap up a campaign.

Okay let's game this out: a genestealer in DW has the following stats compared to its 40k equivalent:

WS: 65 (6 in 40k)
BS: - (0 in 40k)
S: 45 (4 in 40k)
T: 40 (4 in 40k)
Ag: 40 (Initiative is actually 6 in 40k so this is a discrepancy, but it has lightning reflexes, which add twice the agility bonus for initiative rolls in DW)
Int: 35 (not a factor in 40k)
Per: 60 (Could this be initiative- that would translate exactly?)
WP: 45 (Not sure how this translates to the 10 Ld in 40k)
Fel: - (Effectively infinite, as per the hive mind rule on always passing Ld tests)

So the stats actually line up about the same as you'd expect them to, assuming the 'tens' number is the number used in 40k. This should make converting a marine to 40k quite simple- you just take the tens number in their DW sheet as their characteristic in 40k. Add any equipment they have, and you've got a pretty good tabletop representation of them.

But the mortality rate in 40k is extremely high, I hear you cry. Just so- odds are less than great that your typical Space Marine will not survive a game of 40k, which can be a bit annoying when you spend all that time crafting a character just to have him killed by a stray lascannon shot.

My answer to this in game terms would be to keep their fate points active in the game of 40k. So they can still spend fate points to re-roll and burn fate points to survive an otherwise deadly shot. And remember, 40k only deals in casualties, it doesn't distinguish from fatalities the way DW does- it is assumed in 40k that when you hit 0 wounds you are simply out of the battle for one reason or another- you're not necessarily dead.

So I could run my battle in 40k, and even if some of the heroes on the board DO get taken out during the battles, the story will continue on after the battle is over- the story will just have a different outcome based on whether or not they won the battle. If they win, they find the character lying wounded, but not dead, on the battlefield (roll on the critical wounds table). If they lose do the same, but the characters must flee from the battlefield in the face of superior numbers.

I'm going to give this a try when I wrap up my most recent mission, I'll report back.