And anyways, the game is bringing back all those happy memories of conflict and bloodshed, the scourging of heretics and the purging of xenos (I hope I got those right) that the first game (and its expansions) captured about the universe. Nice to see that the story brings back Captain Gabriel Angelus, even if it is as a supporting character. He's still a badass Force Commander.
Okay, maybe it isn't supposed to be happy. WH40k is dark sci-fi on a level no other major writer has even touched, because no one else has the balls to make a universe so sadistic and pessimistic at the same time. But then, when you have a universe when good guys have to be pretty damn evil and oppressive in order for the human race to survive against sci-fi versions of various creatures from modern literature and movies, something's got to break...
This stuff isn't happy. But then, I guess the point is that when true heros do come along, their deeds are made all the more impressive and heroic because (as anyone who is familiar with the WH40k universe understands) of the sheer odds stacked against them. Really, what does it mean to be a hero when one day you could be fighting against Lovecraft inspired space horrors to save a populated world, only to have to destroy that world the next because its a better alternative to allowing the space horrors to corrupt those people? Neither option is truly palatable to the average person, but so are alot choices.
So in a position of being forced to choose between two bad options, you inevitably have to take the lesser of two evils. In the real world, these questions usually boil down to things such as guys having to answer the question "Does this make me look fat?" and presidential elections. In WH40k (not so much in WH Fantasy, which I should have mentioned as a counterpoint earlier) these questions many times involve whether to fight the enemy, or head the problem off by exterminating the very population the enemy is trying to either corrupt or destroy. There's more to it than that, but that is the kind of question that faces many of the major characters at some point or another.
But then, Darth Vader said "The ability to destroy a planet is insignificant next to the power of the force." Well, the power of the force, even the Dark side, is insignificant next to the power the enemies of mankind in the WH40k universe.
And I just got off on a major tangent that jumped around instead of focusing on a central point. But at the same time, this is a subject that could be easily extrapolated on much more than I've said here. Anyways, before I forget, I'll just recommend that anyone interested in WH40k lore should check out just about any of Dan Abnett's books. There are other authors, but he's one of the biggies, known for his running Gaunt's Ghosts series, as well the Eisenhorn and Ravenor series, "...for in the grim dark future, there is only war."