WH40k is the universe for you. Humans ruthlessly slaughter anyone who is a mutant, isn't human, and doesn't worship their God Emperor...and will destroy entire planets with 6 billion plus citizens for benign reasons. The Eldar, this race this character here is, have instigated wars causing millions of deaths...just to save a couple thousand of their own race. The Tau are space communists who believe in working toward a Greater Good. Question one ethic of it and enjoy spending time in a 're-education camp'. They're also known for sterilizing entire planets because their descendants could be upstarts.

And that's like....just a couple races in the universe.

BUT YEAH, if you're interested in like....a gateway into the series, this book was mine. It's a darkish comedy about a nice guy who's kind of a coward doing his best to survive in the Imperial Guard, the human army.